[IMP] app: add a setting to share compiled templates between apps

Previously, when wrapping errors in wrapError, if the error was not an
actual error object, we wouldn't set the cause property on the wrapping
error correctly. The "instanceof Error" check is simply there so that we
can know whether we can add the original errors message to the wrapping
error, but the line that sets the error's cause was mistakenly moved
into that condition.

This commit also fixes the wrapping error's message in the case of
non-Error objects, to avoid having "the following error occurred in
hookname:" with nothing after the colon which is confusing/misleading.

doc/reference/app.md

@@ -55,6 +55,9 @@ The `config` object is an object with some of the following keys:
   [`dev` mode](#dev-mode);
 - **`test (boolean, default=false)`**: `test` mode is the same as `dev` mode, except
   that Owl will not log a message to warn that Owl is in `dev` mode.
+- **`shareTemplates (boolean, default=false)`**: if `true`, each compiled template
+  will be shared between instances of `App`. Useful for speeding test suites, because
+  it prevent recompiling the same templates again and again.
 - **`translatableAttributes (string[])`**: a list of additional attributes that should
   be translated (see [translations](translations.md))
 - **`translateFn (function)`**: a function that will be called by owl to translate

package.json

@@ -1,9 +1,8 @@
 {
   "name": "@odoo/owl",
-  "version": "2.0.0-beta-14",
+  "version": "2.0.0-beta-15",
   "description": "Odoo Web Library (OWL)",
   "main": "dist/owl.cjs.js",
-  "browser": "dist/owl.iife.js",
   "module": "dist/owl.es.js",
   "types": "dist/types/owl.d.ts",
   "files": [

rollup.config.js

@@ -6,6 +6,14 @@ import dts from "rollup-plugin-dts";
 
 let input, output;
 
+const IIFE_FILENAME = "dist/owl.iife.js";
+const CJS_FILENAME = "dist/owl.cjs.js";
+const ES_FILENAME = "dist/owl.es.js";
+
+if (pkg.module !== ES_FILENAME || pkg.main !== CJS_FILENAME) {
+  throw new Error("package.json has been modified. Build script should be updated accordingly");
+}  
+
 const outro = `
 __info__.version = '${pkg.version}';
 __info__.date = '${new Date().toISOString()}';
@@ -23,19 +31,19 @@ switch (process.argv[4]) {
   case "runtime":
     input = "src/runtime/index.ts";
     output = [
-      getConfigForFormat('esm', addSuffix(pkg.module,  'runtime'), outro),
-      getConfigForFormat('cjs', addSuffix(pkg.main,  'runtime'), outro),
-      getConfigForFormat('iife', addSuffix(pkg.browser,  'runtime'), outro),
-      getConfigForFormat('iife', addSuffix(pkg.browser,  'runtime'), outro, true),
+      getConfigForFormat('esm', addSuffix(ES_FILENAME,  'runtime'), outro),
+      getConfigForFormat('cjs', addSuffix(CJS_FILENAME,  'runtime'), outro),
+      getConfigForFormat('iife', addSuffix(IIFE_FILENAME,  'runtime'), outro),
+      getConfigForFormat('iife', addSuffix(IIFE_FILENAME,  'runtime'), outro, true),
     ]
     break;
   default:
     input = "src/index.ts",
     output = [
-      getConfigForFormat('esm', pkg.module, outro),
-      getConfigForFormat('cjs', pkg.main, outro),
-      getConfigForFormat('iife', pkg.browser, outro),
-      getConfigForFormat('iife', pkg.browser, outro, true),
+      getConfigForFormat('esm', ES_FILENAME, outro),
+      getConfigForFormat('cjs', CJS_FILENAME, outro),
+      getConfigForFormat('iife', IIFE_FILENAME, outro),
+      getConfigForFormat('iife', IIFE_FILENAME, outro, true),
     ]
   }
 

src/compiler/code_generator.ts

@@ -30,6 +30,7 @@ import {
   Attrs,
   EventHandlers,
 } from "./parser";
+import { OwlError } from "../runtime/error_handling";
 
 type BlockType = "block" | "text" | "multi" | "list" | "html" | "comment";
 
@@ -535,7 +536,7 @@ export class CodeGenerator {
       .slice(1)
       .map((m) => {
         if (!MODS.has(m)) {
-          throw new Error(`Unknown event modifier: '${m}'`);
+          throw new OwlError(`Unknown event modifier: '${m}'`);
         }
         return `"${m}"`;
       });
@@ -871,8 +872,9 @@ export class CodeGenerator {
     this.define(`key${this.target.loopLevel}`, ast.key ? compileExpr(ast.key) : loopVar);
     if (this.dev) {
       // Throw error on duplicate keys in dev mode
+      this.helpers.add("OwlError");
       this.addLine(
-        `if (keys${block.id}.has(key${this.target.loopLevel})) { throw new Error(\`Got duplicate key in t-foreach: \${key${this.target.loopLevel}}\`)}`
+        `if (keys${block.id}.has(key${this.target.loopLevel})) { throw new OwlError(\`Got duplicate key in t-foreach: \${key${this.target.loopLevel}}\`)}`
       );
       this.addLine(`keys${block.id}.add(key${this.target.loopLevel});`);
     }
@@ -1094,7 +1096,7 @@ export class CodeGenerator {
         name = _name;
         value = `bind(ctx, ${value || undefined})`;
       } else {
-        throw new Error("Invalid prop suffix");
+        throw new OwlError("Invalid prop suffix");
       }
     }
     name = /^[a-z_]+$/i.test(name) ? name : `'${name}'`;

src/compiler/inline_expressions.ts

@@ -1,3 +1,5 @@
+import { OwlError } from "../runtime/error_handling";
+
 /**
  * Owl QWeb Expression Parser
  *
@@ -106,14 +108,14 @@ let tokenizeString: Tokenizer = function (expr) {
       i++;
       cur = expr[i];
       if (!cur) {
-        throw new Error("Invalid expression");
+        throw new OwlError("Invalid expression");
       }
       s += cur;
     }
     i++;
   }
   if (expr[i] !== start) {
-    throw new Error("Invalid expression");
+    throw new OwlError("Invalid expression");
   }
   s += start;
   if (start === "`") {
@@ -223,7 +225,7 @@ export function tokenize(expr: string): Token[] {
     error = e; // Silence all errors and throw a generic error below
   }
   if (current.length || error) {
-    throw new Error(`Tokenizer error: could not tokenize \`${expr}\``);
+    throw new OwlError(`Tokenizer error: could not tokenize \`${expr}\``);
   }
   return result;
 }

src/compiler/parser.ts

@@ -1,3 +1,5 @@
+import { OwlError } from "../runtime/error_handling";
+
 // -----------------------------------------------------------------------------
 // AST Type definition
 // -----------------------------------------------------------------------------
@@ -319,7 +321,7 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
     return null;
   }
   if (tagName.startsWith("block-")) {
-    throw new Error(`Invalid tag name: '${tagName}'`);
+    throw new OwlError(`Invalid tag name: '${tagName}'`);
   }
   ctx = Object.assign({}, ctx);
   if (tagName === "pre") {
@@ -340,13 +342,15 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
     const value = node.getAttribute(attr)!;
     if (attr.startsWith("t-on")) {
       if (attr === "t-on") {
-        throw new Error("Missing event name with t-on directive");
+        throw new OwlError("Missing event name with t-on directive");
       }
       on = on || {};
       on[attr.slice(5)] = value;
     } else if (attr.startsWith("t-model")) {
       if (!["input", "select", "textarea"].includes(tagName)) {
-        throw new Error("The t-model directive only works with <input>, <textarea> and <select>");
+        throw new OwlError(
+          "The t-model directive only works with <input>, <textarea> and <select>"
+        );
       }
 
       let baseExpr, expr;
@@ -359,7 +363,7 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
         baseExpr = value.slice(0, index);
         expr = value.slice(index + 1, -1);
       } else {
-        throw new Error(`Invalid t-model expression: "${value}" (it should be assignable)`);
+        throw new OwlError(`Invalid t-model expression: "${value}" (it should be assignable)`);
       }
 
       const typeAttr = node.getAttribute("type");
@@ -390,10 +394,10 @@ function parseDOMNode(node: Element, ctx: ParsingContext): AST | null {
         ctx.tModelInfo = model;
       }
     } else if (attr.startsWith("block-")) {
-      throw new Error(`Invalid attribute: '${attr}'`);
+      throw new OwlError(`Invalid attribute: '${attr}'`);
     } else if (attr !== "t-name") {
       if (attr.startsWith("t-") && !attr.startsWith("t-att")) {
-        throw new Error(`Unknown QWeb directive: '${attr}'`);
+        throw new OwlError(`Unknown QWeb directive: '${attr}'`);
       }
       const tModel = ctx.tModelInfo;
       if (tModel && ["t-att-value", "t-attf-value"].includes(attr)) {
@@ -447,7 +451,7 @@ function parseTEscNode(node: Element, ctx: ParsingContext): AST | null {
     };
   }
   if (ast.type === ASTType.TComponent) {
-    throw new Error("t-esc is not supported on Component nodes");
+    throw new OwlError("t-esc is not supported on Component nodes");
   }
   return tesc;
 }
@@ -503,7 +507,7 @@ function parseTForEach(node: Element, ctx: ParsingContext): AST | null {
   node.removeAttribute("t-as");
   const key = node.getAttribute("t-key");
   if (!key) {
-    throw new Error(
+    throw new OwlError(
       `"Directive t-foreach should always be used with a t-key!" (expression: t-foreach="${collection}" t-as="${elem}")`
     );
   }
@@ -686,7 +690,9 @@ function parseComponent(node: Element, ctx: ParsingContext): AST | null {
   let isDynamic = node.hasAttribute("t-component");
 
   if (isDynamic && name !== "t") {
-    throw new Error(`Directive 't-component' can only be used on <t> nodes (used on a <${name}>)`);
+    throw new OwlError(
+      `Directive 't-component' can only be used on <t> nodes (used on a <${name}>)`
+    );
   }
 
   if (!(firstLetter === firstLetter.toUpperCase() || isDynamic)) {
@@ -713,7 +719,7 @@ function parseComponent(node: Element, ctx: ParsingContext): AST | null {
         on[name.slice(5)] = value;
       } else {
         const message = directiveErrorMap.get(name.split("-").slice(0, 2).join("-"));
-        throw new Error(message || `unsupported directive on Component: ${name}`);
+        throw new OwlError(message || `unsupported directive on Component: ${name}`);
       }
     } else {
       props = props || {};
@@ -729,7 +735,7 @@ function parseComponent(node: Element, ctx: ParsingContext): AST | null {
     const slotNodes = Array.from(clone.querySelectorAll("[t-set-slot]"));
     for (let slotNode of slotNodes) {
       if (slotNode.tagName !== "t") {
-        throw new Error(
+        throw new OwlError(
           `Directive 't-set-slot' can only be used on <t> nodes (used on a <${slotNode.tagName}>)`
         );
       }
@@ -904,7 +910,7 @@ function normalizeTIf(el: Element) {
     let nattr = (name: string) => +!!node.getAttribute(name);
     if (prevElem && (pattr("t-if") || pattr("t-elif"))) {
       if (pattr("t-foreach")) {
-        throw new Error(
+        throw new OwlError(
           "t-if cannot stay at the same level as t-foreach when using t-elif or t-else"
         );
       }
@@ -913,19 +919,19 @@ function normalizeTIf(el: Element) {
           return a + b;
         }) > 1
       ) {
-        throw new Error("Only one conditional branching directive is allowed per node");
+        throw new OwlError("Only one conditional branching directive is allowed per node");
       }
       // All text (with only spaces) and comment nodes (nodeType 8) between
       // branch nodes are removed
       let textNode;
       while ((textNode = node.previousSibling) !== prevElem) {
         if (textNode!.nodeValue!.trim().length && textNode!.nodeType !== 8) {
-          throw new Error("text is not allowed between branching directives");
+          throw new OwlError("text is not allowed between branching directives");
         }
         textNode!.remove();
       }
     } else {
-      throw new Error(
+      throw new OwlError(
         "t-elif and t-else directives must be preceded by a t-if or t-elif directive"
       );
     }
@@ -946,7 +952,7 @@ function normalizeTEsc(el: Element) {
   );
   for (const el of elements) {
     if (el.childNodes.length) {
-      throw new Error("Cannot have t-esc on a component that already has content");
+      throw new OwlError("Cannot have t-esc on a component that already has content");
     }
     const value = el.getAttribute("t-esc");
     el.removeAttribute("t-esc");
@@ -1000,7 +1006,7 @@ function parseXML(xml: string): XMLDocument {
         }
       }
     }
-    throw new Error(msg);
+    throw new OwlError(msg);
   }
 
   return doc;

src/runtime/app.ts

@@ -1,6 +1,6 @@
 import { Component, ComponentConstructor, Props } from "./component";
 import { ComponentNode } from "./component_node";
-import { nodeErrorHandlers } from "./error_handling";
+import { nodeErrorHandlers, OwlError } from "./error_handling";
 import { Fiber, MountOptions } from "./fibers";
 import { Scheduler } from "./scheduler";
 import { validateProps } from "./template_helpers";
@@ -154,9 +154,9 @@ export class App<
         if (isStatic) {
           C = parent.constructor.components[name as any];
           if (!C) {
-            throw new Error(`Cannot find the definition of component "${name}"`);
+            throw new OwlError(`Cannot find the definition of component "${name}"`);
           } else if (!(C.prototype instanceof Component)) {
-            throw new Error(
+            throw new OwlError(
               `"${name}" is not a Component. It must inherit from the Component class`
             );
           }

src/runtime/blockdom/block_compiler.ts

@@ -1,3 +1,4 @@
+import { OwlError } from "../error_handling";
 import {
   attrsSetter,
   attrsUpdater,
@@ -245,7 +246,7 @@ function buildTree(
       };
     }
   }
-  throw new Error("boom");
+  throw new OwlError("boom");
 }
 
 function addRef(tree: IntermediateTree) {

src/runtime/component_node.ts

@@ -1,7 +1,7 @@
 import type { App, Env } from "./app";
 import { BDom, VNode } from "./blockdom";
 import { Component, ComponentConstructor, Props } from "./component";
-import { fibersInError, handleError } from "./error_handling";
+import { fibersInError, handleError, OwlError } from "./error_handling";
 import { Fiber, makeChildFiber, makeRootFiber, MountFiber, MountOptions } from "./fibers";
 import {
   clearReactivesForCallback,
@@ -18,7 +18,7 @@ let currentNode: ComponentNode | null = null;
 
 export function getCurrent(): ComponentNode {
   if (!currentNode) {
-    throw new Error("No active component (a hook function should only be called in 'setup')");
+    throw new OwlError("No active component (a hook function should only be called in 'setup')");
   }
   return currentNode;
 }
@@ -83,7 +83,6 @@ export class ComponentNode<P extends Props = any, E = any> implements VNode<Comp
 
   renderFn: Function;
   parent: ComponentNode | null;
-  level: number;
   childEnv: Env;
   children: { [key: string]: ComponentNode } = Object.create(null);
   refs: any = {};
@@ -108,7 +107,6 @@ export class ComponentNode<P extends Props = any, E = any> implements VNode<Comp
     this.parent = parent;
     this.props = props;
     this.parentKey = parentKey;
-    this.level = parent ? parent.level + 1 : 0;
     const defaultProps = C.defaultProps;
     props = Object.assign({}, props);
     if (defaultProps) {

src/runtime/error_handling.ts

@@ -1,6 +1,11 @@
 import type { ComponentNode } from "./component_node";
 import type { Fiber } from "./fibers";
 
+// Custom error class that wraps error that happen in the owl lifecycle
+export class OwlError extends Error {
+  cause?: any;
+}
+
 // Maps fibers to thrown errors
 export const fibersInError: WeakMap<Fiber, any> = new WeakMap();
 export const nodeErrorHandlers: WeakMap<ComponentNode, ((error: any) => void)[]> = new WeakMap();
@@ -37,7 +42,14 @@ function _handleError(node: ComponentNode | null, error: any): boolean {
 
 type ErrorParams = { error: any } & ({ node: ComponentNode } | { fiber: Fiber });
 export function handleError(params: ErrorParams) {
-  const error = params.error;
+  let { error } = params;
+  // Wrap error if it wasn't wrapped by wrapError (ie when not in dev mode)
+  if (!(error instanceof OwlError)) {
+    error = Object.assign(
+      new OwlError(`An error occured in the owl lifecycle (see this Error's "cause" property)`),
+      { cause: error }
+    );
+  }
   const node = "node" in params ? params.node : params.fiber.node;
   const fiber = "fiber" in params ? params.fiber : node.fiber!;
 

src/runtime/event_handling.ts

@@ -1,5 +1,6 @@
 import { filterOutModifiersFromData } from "./blockdom/config";
 import { STATUS } from "./status";
+import { OwlError } from "./error_handling";
 
 export const mainEventHandler = (data: any, ev: Event, currentTarget?: EventTarget | null) => {
   const { data: _data, modifiers } = filterOutModifiersFromData(data);
@@ -33,7 +34,7 @@ export const mainEventHandler = (data: any, ev: Event, currentTarget?: EventTarg
   if (Object.hasOwnProperty.call(data, 0)) {
     const handler = data[0];
     if (typeof handler !== "function") {
-      throw new Error(`Invalid handler (expected a function, received: '${handler}')`);
+      throw new OwlError(`Invalid handler (expected a function, received: '${handler}')`);
     }
     let node = data[1] ? data[1].__owl__ : null;
     if (node ? node.status === STATUS.MOUNTED : true) {

src/runtime/fibers.ts

@@ -1,6 +1,6 @@
 import { BDom, mount } from "./blockdom";
 import type { ComponentNode } from "./component_node";
-import { fibersInError, handleError } from "./error_handling";
+import { fibersInError, handleError, OwlError } from "./error_handling";
 import { STATUS } from "./status";
 
 export function makeChildFiber(node: ComponentNode, parent: Fiber): Fiber {
@@ -43,7 +43,7 @@ export function makeRootFiber(node: ComponentNode): Fiber {
 }
 
 function throwOnRender() {
-  throw new Error("Attempted to render cancelled fiber");
+  throw new OwlError("Attempted to render cancelled fiber");
 }
 
 /**

src/runtime/index.ts

@@ -54,5 +54,6 @@ export {
   onError,
 } from "./lifecycle_hooks";
 export { validate } from "./validation";
+export { OwlError } from "./error_handling";
 
 export const __info__ = {};

src/runtime/lifecycle_hooks.ts

@@ -1,21 +1,30 @@
 import { getCurrent } from "./component_node";
-import { nodeErrorHandlers } from "./error_handling";
+import { nodeErrorHandlers, OwlError } from "./error_handling";
 
 const TIMEOUT = Symbol("timeout");
 function wrapError(fn: (...args: any[]) => any, hookName: string) {
-  const error = new Error(`The following error occurred in ${hookName}: `) as Error & {
+  const error = new OwlError(`The following error occurred in ${hookName}: `) as Error & {
     cause: any;
   };
-  const timeoutError = new Error(`${hookName}'s promise hasn't resolved after 3 seconds`);
+  const timeoutError = new OwlError(`${hookName}'s promise hasn't resolved after 3 seconds`);
   const node = getCurrent();
   return (...args: any[]) => {
+    const onError = (cause: any) => {
+      error.cause = cause;
+      if (cause instanceof Error) {
+        error.message += `"${cause.message}"`;
+      } else {
+        error.message = `Something that is not an Error was thrown in ${hookName} (see this Error's "cause" property)`;
+      }
+      throw error;
+    };
     try {
       const result = fn(...args);
       if (result instanceof Promise) {
         if (hookName === "onWillStart" || hookName === "onWillUpdateProps") {
           const fiber = node.fiber;
           Promise.race([
-            result,
+            result.catch(() => {}),
             new Promise((resolve) => setTimeout(() => resolve(TIMEOUT), 3000)),
           ]).then((res) => {
             if (res === TIMEOUT && node.fiber === fiber) {
@@ -23,20 +32,11 @@ function wrapError(fn: (...args: any[]) => any, hookName: string) {
             }
           });
         }
-        return result.catch((cause) => {
-          error.cause = cause;
-          if (cause instanceof Error) {
-            error.message += `"${cause.message}"`;
-          }
-          throw error;
-        });
+        return result.catch(onError);
       }
       return result;
     } catch (cause) {
-      if (cause instanceof Error) {
-        error.message += `"${cause.message}"`;
-      }
-      throw error;
+      onError(cause);
     }
   };
 }

src/runtime/portal.ts

@@ -1,6 +1,7 @@
 import { onWillUnmount } from "./lifecycle_hooks";
 import { BDom, text, VNode } from "./blockdom";
 import { Component } from "./component";
+import { OwlError } from "./error_handling";
 
 const VText: any = text("").constructor;
 
@@ -24,7 +25,7 @@ class VPortal extends VText implements Partial<VNode<VPortal>> {
       }
       this.target = el && el.querySelector(this.selector);
       if (!this.target) {
-        throw new Error("invalid portal target");
+        throw new OwlError("invalid portal target");
       }
     }
     this.realBDom!.mount(this.target!, null);

src/runtime/reactivity.ts

@@ -1,4 +1,5 @@
 import { Callback } from "./utils";
+import { OwlError } from "./error_handling";
 
 // Allows to get the target of a Reactive (used for making a new Reactive from the underlying object)
 export const TARGET = Symbol("Target");
@@ -197,7 +198,7 @@ export function reactive<T extends Target>(
   callback: Callback = () => {}
 ): Reactive<T> | NonReactive<T> {
   if (!canBeMadeReactive(target)) {
-    throw new Error(`Cannot make the given value reactive`);
+    throw new OwlError(`Cannot make the given value reactive`);
   }
   if (SKIP in target) {
     return target as NonReactive<T>;

src/runtime/template_helpers.ts

@@ -4,6 +4,7 @@ import { html } from "./blockdom/index";
 import { isOptional, validateSchema } from "./validation";
 import type { ComponentConstructor } from "./component";
 import { markRaw } from "./reactivity";
+import { OwlError } from "./error_handling";
 
 const ObjectCreate = Object.create;
 /**
@@ -70,7 +71,7 @@ function prepareList(collection: any): [any[], any[], number, any[]] {
     values = Object.keys(collection);
     keys = Object.values(collection);
   } else {
-    throw new Error("Invalid loop expression");
+    throw new OwlError("Invalid loop expression");
   }
   const n = values.length;
   return [keys, values, n, new Array(n)];
@@ -191,7 +192,7 @@ function multiRefSetter(refs: RefMap, name: string): RefSetter {
     if (el) {
       count++;
       if (count > 1) {
-        throw new Error("Cannot have 2 elements with same ref name at the same time");
+        throw new OwlError("Cannot have 2 elements with same ref name at the same time");
       }
     }
     if (count === 0 || el) {
@@ -233,7 +234,7 @@ export function validateProps<P>(name: string | ComponentConstructor<P>, props:
         : name in schema && !("*" in schema) && !isOptional(schema[name]);
     for (let p in defaultProps) {
       if (isMandatory(p)) {
-        throw new Error(
+        throw new OwlError(
           `A default value cannot be defined for a mandatory prop (name: '${p}', component: ${ComponentClass.name})`
         );
       }
@@ -242,7 +243,9 @@ export function validateProps<P>(name: string | ComponentConstructor<P>, props:
 
   const errors = validateSchema(props, schema);
   if (errors.length) {
-    throw new Error(`Invalid props for component '${ComponentClass.name}': ` + errors.join(", "));
+    throw new OwlError(
+      `Invalid props for component '${ComponentClass.name}': ` + errors.join(", ")
+    );
   }
 }
 
@@ -264,4 +267,5 @@ export const helpers = {
   bind,
   createCatcher,
   markRaw,
+  OwlError,
 };

src/runtime/template_set.ts

@@ -3,6 +3,7 @@ import { comment, createBlock, html, list, multi, text, toggler } from "./blockd
 import { getCurrent } from "./component_node";
 import { Portal, portalTemplate } from "./portal";
 import { helpers } from "./template_helpers";
+import { OwlError } from "./error_handling";
 
 const bdom = { text, createBlock, list, multi, html, toggler, comment };
 
@@ -31,16 +32,22 @@ function parseXML(xml: string): Document {
         }
       }
     }
-    throw new Error(msg);
+    throw new OwlError(msg);
   }
   return doc;
 }
 
+const sharedTemplates: Map<
+  Function | undefined,
+  { [key: string]: { [name: string]: TemplateFunction } }
+> = new Map();
+
 export interface TemplateSetConfig {
   dev?: boolean;
   translatableAttributes?: string[];
   translateFn?: (s: string) => string;
   templates?: string | Document;
+  shareTemplates?: boolean;
 }
 
 export class TemplateSet {
@@ -50,12 +57,27 @@ export class TemplateSet {
   dev: boolean;
   rawTemplates: typeof globalTemplates = Object.create(globalTemplates);
   templates: { [name: string]: Template } = {};
+  templateFunctions: { [name: string]: TemplateFunction } = {};
   translateFn?: (s: string) => string;
   translatableAttributes?: string[];
   Portal = Portal;
 
   constructor(config: TemplateSetConfig = {}) {
     this.dev = config.dev || false;
+    if (config.shareTemplates) {
+      let cache = sharedTemplates.get(this.translateFn);
+      if (!cache) {
+        cache = {};
+        sharedTemplates.set(this.translateFn, cache);
+      }
+      let key = `${this.dev ? "d" : "p"}${(this.translatableAttributes || []).toString()}`;
+      let templates = cache[key];
+      if (!templates) {
+        cache[key] = {};
+        templates = cache[key];
+      }
+      this.templateFunctions = templates;
+    }
     this.translateFn = config.translateFn;
     this.translatableAttributes = config.translatableAttributes;
     if (config.templates) {
@@ -76,7 +98,7 @@ export class TemplateSet {
       if (currentAsString === newAsString) {
         return;
       }
-      throw new Error(`Template ${name} already defined with different content`);
+      throw new OwlError(`Template ${name} already defined with different content`);
     }
     this.rawTemplates[name] = template;
   }
@@ -95,17 +117,21 @@ export class TemplateSet {
 
   getTemplate(name: string): Template {
     if (!(name in this.templates)) {
-      const rawTemplate = this.rawTemplates[name];
-      if (rawTemplate === undefined) {
-        let extraInfo = "";
-        try {
-          const componentName = getCurrent().component.constructor.name;
-          extraInfo = ` (for component "${componentName}")`;
-        } catch {}
-        throw new Error(`Missing template: "${name}"${extraInfo}`);
+      let templateFn = this.templateFunctions[name];
+      if (!templateFn) {
+        const rawTemplate = this.rawTemplates[name];
+        if (rawTemplate === undefined) {
+          let extraInfo = "";
+          try {
+            const componentName = getCurrent().component.constructor.name;
+            extraInfo = ` (for component "${componentName}")`;
+          } catch {}
+          throw new OwlError(`Missing template: "${name}"${extraInfo}`);
+        }
+        const isFn = typeof rawTemplate === "function" && !(rawTemplate instanceof Element);
+        templateFn = isFn ? rawTemplate : this._compileTemplate(name, rawTemplate);
+        this.templateFunctions[name] = templateFn;
       }
-      const isFn = typeof rawTemplate === "function" && !(rawTemplate instanceof Element);
-      const templateFn = isFn ? rawTemplate : this._compileTemplate(name, rawTemplate);
       // first add a function to lazily get the template, in case there is a
       // recursive call to the template name
       const templates = this.templates;
@@ -119,7 +145,7 @@ export class TemplateSet {
   }
 
   _compileTemplate(name: string, template: string | Element): ReturnType<typeof compile> {
-    throw new Error(`Unable to compile a template. Please use owl full build instead`);
+    throw new OwlError(`Unable to compile a template. Please use owl full build instead`);
   }
 
   callTemplate(owner: any, subTemplate: string, ctx: any, parent: any, key: any): any {

src/runtime/utils.ts

@@ -1,3 +1,4 @@
+import { OwlError } from "./error_handling";
 export type Callback = () => void;
 
 /**
@@ -28,10 +29,10 @@ export function batched(callback: Callback): Callback {
 
 export function validateTarget(target: HTMLElement) {
   if (!(target instanceof HTMLElement)) {
-    throw new Error("Cannot mount component: the target is not a valid DOM element");
+    throw new OwlError("Cannot mount component: the target is not a valid DOM element");
   }
   if (!document.body.contains(target)) {
-    throw new Error("Cannot mount a component on a detached dom node");
+    throw new OwlError("Cannot mount a component on a detached dom node");
   }
 }
 
@@ -54,7 +55,7 @@ export function whenReady(fn?: any): Promise<void> {
 export async function loadFile(url: string): Promise<string> {
   const result = await fetch(url);
   if (!result.ok) {
-    throw new Error("Error while fetching xml templates");
+    throw new OwlError("Error while fetching xml templates");
   }
   return await result.text();
 }

src/runtime/validation.ts

@@ -1,3 +1,5 @@
+import { OwlError } from "./error_handling";
+
 type BaseType =
   | typeof String
   | typeof Boolean
@@ -70,7 +72,7 @@ function toSchema(spec: SimplifiedSchema): NormalizedSchema {
 export function validate(obj: { [key: string]: any }, spec: Schema) {
   let errors = validateSchema(obj, spec);
   if (errors.length) {
-    throw new Error("Invalid object: " + errors.join(", "));
+    throw new OwlError("Invalid object: " + errors.join(", "));
   }
 }
 

tests/components/__snapshots__/error_handling.test.ts.snap

@@ -101,6 +101,72 @@ exports[`basics simple catchError 2`] = `
 }"
 `;
 
+exports[`can catch errors Errors have the right cause 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['state'].value);
+  }
+}"
+`;
+
+exports[`can catch errors Errors in owl lifecycle are wrapped in dev mode: async hook 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['state'].value);
+  }
+}"
+`;
+
+exports[`can catch errors Errors in owl lifecycle are wrapped out of dev mode: async hook 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['state'].value);
+  }
+}"
+`;
+
+exports[`can catch errors Errors in owl lifecycle are wrapped outside dev mode: sync hook 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['state'].value);
+  }
+}"
+`;
+
+exports[`can catch errors Thrown values that are not errors are wrapped in dev mode 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['state'].value);
+  }
+}"
+`;
+
+exports[`can catch errors Thrown values that are not errors are wrapped outside dev mode 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    return text(ctx['state'].value);
+  }
+}"
+`;
+
 exports[`can catch errors an error in onWillDestroy 1`] = `
 "function anonymous(app, bdom, helpers
 ) {
@@ -1296,3 +1362,16 @@ exports[`errors and promises errors in rerender 1`] = `
   }
 }"
 `;
+
+exports[`errors and promises wrapped errors in async code are correctly caught 1`] = `
+"function anonymous(app, bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, comment } = bdom;
+  
+  let block1 = createBlock(\`<div>abc</div>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    return block1();
+  }
+}"
+`;

tests/components/__snapshots__/t_foreach.test.ts.snap

@@ -43,7 +43,7 @@ exports[`list of components crash on duplicate key in dev mode 1`] = `
 "function anonymous(app, bdom, helpers
 ) {
   let { text, createBlock, list, multi, html, toggler, comment } = bdom;
-  let { prepareList, withKey } = helpers;
+  let { prepareList, OwlError, withKey } = helpers;
   const comp1 = app.createComponent(\`Child\`, true, false, false, true);
   
   return function template(ctx, node, key = \\"\\") {
@@ -53,7 +53,7 @@ exports[`list of components crash on duplicate key in dev mode 1`] = `
     for (let i1 = 0; i1 < l_block1; i1++) {
       ctx[\`item\`] = v_block1[i1];
       const key1 = 'child';
-      if (keys1.has(key1)) { throw new Error(\`Got duplicate key in t-foreach: \${key1}\`)}
+      if (keys1.has(key1)) { throw new OwlError(\`Got duplicate key in t-foreach: \${key1}\`)}
       keys1.add(key1);
       const props1 = {};
       helpers.validateProps(\`Child\`, props1, ctx);

tests/components/error_handling.test.ts

@@ -19,6 +19,7 @@ import {
   snapshotEverything,
   useLogLifecycle,
 } from "../helpers";
+import { OwlError } from "../../src/runtime/error_handling";
 
 let fixture: HTMLElement;
 
@@ -159,16 +160,17 @@ describe("errors and promises", () => {
       static template = xml`<div><t t-esc="this.will.crash"/></div>`;
     }
 
-    let error: Error;
+    let error: OwlError;
     try {
       await mount(App, fixture);
     } catch (e) {
-      error = e as Error;
+      error = e as OwlError;
     }
     expect(error!).toBeDefined();
+    expect(error!.cause).toBeDefined();
     const regexp =
       /Cannot read properties of undefined \(reading 'crash'\)|Cannot read property 'crash' of undefined/g;
-    expect(error!.message).toMatch(regexp);
+    expect(error!.cause.message).toMatch(regexp);
     expect(mockConsoleError).toBeCalledTimes(0);
     expect(mockConsoleError).toBeCalledTimes(0);
   });
@@ -183,14 +185,15 @@ describe("errors and promises", () => {
       }
     }
 
-    let error: Error;
+    let error: OwlError;
     try {
       await mount(App, fixture);
     } catch (e) {
-      error = e as Error;
+      error = e as OwlError;
     }
     expect(error!).toBeDefined();
-    expect(error!.message).toBe("boom");
+    expect(error!.cause).toBeDefined();
+    expect(error!.cause.message).toBe("boom");
     expect(fixture.innerHTML).toBe("");
     expect(mockConsoleError).toBeCalledTimes(0);
     expect(mockConsoleWarn).toBeCalledTimes(1);
@@ -264,6 +267,30 @@ describe("errors and promises", () => {
     expect(error!.message).toBe("Tokenizer error: could not tokenize `{ 'invalid: 5 }`");
   });
 
+  test("wrapped errors in async code are correctly caught", async () => {
+    class Root extends Component {
+      static template = xml`<div>abc</div>`;
+      setup() {
+        onWillStart(async () => {
+          await Promise.resolve();
+          throw new Error("boom in onWillStart");
+        });
+      }
+    }
+
+    let error: any;
+    try {
+      await mount(Root, fixture, { test: true });
+    } catch (e) {
+      error = e;
+    }
+    expect(error!).toBeDefined();
+    expect(error!.message).toBe(
+      `The following error occurred in onWillStart: "boom in onWillStart"`
+    );
+    await new Promise((r) => setTimeout(r, 0)); // wait for the rejection event to bubble
+  });
+
   test("an error in willPatch call will reject the render promise", async () => {
     class Root extends Component {
       static template = xml`<div><t t-esc="val"/></div>`;
@@ -320,16 +347,17 @@ describe("errors and promises", () => {
       static components = { Child };
     }
 
-    let error: Error;
+    let error: OwlError;
     try {
       await mount(App, fixture);
     } catch (e) {
-      error = e as Error;
+      error = e as OwlError;
     }
     expect(error!).toBeDefined();
+    expect(error!.cause).toBeDefined();
     const regexp =
       /Cannot read properties of undefined \(reading 'crash'\)|Cannot read property 'crash' of undefined/g;
-    expect(error!.message).toMatch(regexp);
+    expect(error!.cause.message).toMatch(regexp);
     expect(mockConsoleError).toBeCalledTimes(0);
     expect(mockConsoleWarn).toBeCalledTimes(1);
   });
@@ -339,7 +367,7 @@ describe("errors and promises", () => {
       static template = xml`<div><t t-if="flag" t-esc="this.will.crash"/></div>`;
       flag = false;
       setup() {
-        onError((e) => (error = e));
+        onError(({ cause }) => (error = cause));
       }
     }
 
@@ -366,16 +394,17 @@ describe("errors and promises", () => {
       static components = { Child };
     }
 
-    let error: Error;
+    let error: OwlError;
     try {
       await mount(Parent, fixture);
     } catch (e) {
-      error = e as Error;
+      error = e as OwlError;
     }
     expect(error!).toBeDefined();
+    expect(error!.cause).toBeDefined();
     const regexp =
       /Cannot read properties of undefined \(reading 'y'\)|Cannot read property 'y' of undefined/g;
-    expect(error!.message).toMatch(regexp);
+    expect(error!.cause.message).toMatch(regexp);
     expect(mockConsoleError).toBeCalledTimes(0);
     expect(mockConsoleWarn).toBeCalledTimes(1);
   });
@@ -482,6 +511,146 @@ describe("can catch errors", () => {
     );
   });
 
+  test("Errors have the right cause", async () => {
+    const err = new Error("test error");
+    class Root extends Component {
+      static template = xml`<t t-esc="state.value"/>`;
+      state = useState({ value: 1 });
+
+      setup() {
+        onMounted(() => {
+          throw err;
+        });
+      }
+    }
+    let e: OwlError;
+    try {
+      await mount(Root, fixture, { test: true });
+    } catch (error) {
+      e = error as OwlError;
+    }
+    expect(e!.message).toBe(`The following error occurred in onMounted: "test error"`);
+    expect(e!.cause).toBe(err);
+  });
+
+  test("Errors in owl lifecycle are wrapped in dev mode: async hook", async () => {
+    const err = new Error("test error");
+    class Root extends Component {
+      static template = xml`<t t-esc="state.value"/>`;
+      state = useState({ value: 1 });
+
+      setup() {
+        onWillStart(async () => {
+          await nextMicroTick();
+          throw err;
+        });
+      }
+    }
+    let e: OwlError;
+    try {
+      await mount(Root, fixture, { test: true });
+    } catch (error) {
+      e = error as OwlError;
+    }
+    expect(e!.message).toBe(`The following error occurred in onWillStart: "test error"`);
+    expect(e!.cause).toBe(err);
+  });
+
+  test("Errors in owl lifecycle are wrapped outside dev mode: sync hook", async () => {
+    const err = new Error("test error");
+    class Root extends Component {
+      static template = xml`<t t-esc="state.value"/>`;
+      state = useState({ value: 1 });
+
+      setup() {
+        onMounted(() => {
+          throw err;
+        });
+      }
+    }
+    let e: OwlError;
+    try {
+      await mount(Root, fixture);
+    } catch (error) {
+      e = error as OwlError;
+    }
+    expect(e!.message).toBe(
+      `An error occured in the owl lifecycle (see this Error's "cause" property)`
+    );
+    expect(e!.cause).toBe(err);
+  });
+
+  test("Errors in owl lifecycle are wrapped out of dev mode: async hook", async () => {
+    const err = new Error("test error");
+    class Root extends Component {
+      static template = xml`<t t-esc="state.value"/>`;
+      state = useState({ value: 1 });
+
+      setup() {
+        onWillStart(async () => {
+          await nextMicroTick();
+          throw err;
+        });
+      }
+    }
+    let e: OwlError;
+    try {
+      await mount(Root, fixture);
+    } catch (error) {
+      e = error as OwlError;
+    }
+    expect(e!.message).toBe(
+      `An error occured in the owl lifecycle (see this Error's "cause" property)`
+    );
+    expect(e!.cause).toBe(err);
+  });
+
+  test("Thrown values that are not errors are wrapped in dev mode", async () => {
+    class Root extends Component {
+      static template = xml`<t t-esc="state.value"/>`;
+      state = useState({ value: 1 });
+
+      setup() {
+        onMounted(() => {
+          throw "This is not an error";
+        });
+      }
+    }
+    let e: OwlError;
+    try {
+      await mount(Root, fixture, { test: true });
+    } catch (error) {
+      e = error as OwlError;
+    }
+    expect(e!.message).toBe(
+      `Something that is not an Error was thrown in onMounted (see this Error's "cause" property)`
+    );
+    expect(e!.cause).toBe("This is not an error");
+  });
+
+  test("Thrown values that are not errors are wrapped outside dev mode", async () => {
+    class Root extends Component {
+      static template = xml`<t t-esc="state.value"/>`;
+      state = useState({ value: 1 });
+
+      setup() {
+        onMounted(() => {
+          throw "This is not an error";
+        });
+      }
+    }
+    let e: OwlError;
+    try {
+      await mount(Root, fixture);
+    } catch (error) {
+      e = error as OwlError;
+    }
+    expect(e!.message).toBe(
+      `An error occured in the owl lifecycle (see this Error's "cause" property)`
+    );
+    expect(e!.cause).toBe("This is not an error");
+  });
+
   test("can catch an error in the initial call of a component render function (parent mounted)", async () => {
     class ErrorComponent extends Component {
       static template = xml`<div>hey<t t-esc="state.this.will.crash"/></div>`;
@@ -1180,8 +1349,8 @@ describe("can catch errors", () => {
     class Catch extends Component {
       static template = xml`<t t-slot="default" />`;
       setup() {
-        onError((error) => {
-          this.props.onError(error);
+        onError(({ cause }) => {
+          this.props.onError(cause);
         });
       }
     }

tests/components/hooks.test.ts

@@ -653,7 +653,7 @@ describe("hooks", () => {
       try {
         await mount(MyComponent, fixture);
       } catch (e: any) {
-        expect(e.message).toBe("Intentional error");
+        expect(e.cause.message).toBe("Intentional error");
       }
       // no console.error because the error has been caught in this test
       expect(console.error).toHaveBeenCalledTimes(0);

tests/components/style_class.test.ts

@@ -1,3 +1,4 @@
+import { OwlError } from "../../src/runtime/error_handling";
 import { Component, mount, onMounted, useState, xml } from "../../src";
 import { makeTestFixture, nextTick, snapshotEverything } from "../helpers";
 
@@ -346,16 +347,17 @@ describe("style and class handling", () => {
       static template = xml`<Child class="'a'"/>`;
       static components = { Child };
     }
-    let error: Error;
+    let error: OwlError;
     try {
       await mount(ParentWidget, fixture);
     } catch (e) {
-      error = e as Error;
+      error = e as OwlError;
     }
     expect(error!).toBeDefined();
+    expect(error!.cause).toBeDefined();
     const regexp =
       /Cannot read properties of undefined \(reading 'crash'\)|Cannot read property 'crash' of undefined/g;
-    expect(error!.message).toMatch(regexp);
+    expect(error!.cause.message).toMatch(regexp);
     expect(fixture.innerHTML).toBe("");
     expect(mockConsoleWarn).toBeCalledTimes(1);
   });

tests/helpers.ts

@@ -19,6 +19,7 @@ import { helpers } from "../src/runtime/template_helpers";
 import { TemplateSet, globalTemplates } from "../src/runtime/template_set";
 import { BDom } from "../src/runtime/blockdom";
 import { compile } from "../src/compiler";
+import { OwlError } from "../src/runtime/error_handling";
 
 const mount = blockDom.mount;
 
@@ -221,7 +222,7 @@ export async function editInput(input: HTMLInputElement | HTMLTextAreaElement, v
 afterEach(() => {
   if (steps.length) {
     steps.splice(0);
-    throw new Error("Remaining steps! Should be checked by a .toBeLogged() assertion!");
+    throw new OwlError("Remaining steps! Should be checked by a .toBeLogged() assertion!");
   }
 });
 

tests/misc/portal.test.ts

@@ -1,3 +1,4 @@
+import { OwlError } from "../../src/runtime/error_handling";
 import {
   App,
   Component,
@@ -499,7 +500,7 @@ describe("Portal", () => {
         </div>`;
       state = { error: false };
       setup() {
-        onError((e) => (error = e));
+        onError(({ cause }) => (error = cause));
       }
     }
     addOutsideDiv(fixture);
@@ -958,14 +959,15 @@ describe("Portal: Props validation", () => {
           </t>
         </div>`;
     }
-    let error: Error;
+    let error: OwlError;
     try {
       await mount(Parent, fixture, { dev: true });
     } catch (e) {
-      error = e as Error;
+      error = e as OwlError;
     }
     expect(error!).toBeDefined();
-    expect(error!.message).toBe(`' ' is not a valid selector`);
+    expect(error!.cause).toBeDefined();
+    expect(error!.cause.message).toBe(`' ' is not a valid selector`);
   });
 
   test("target must be a valid selector 2", async () => {