[IMP] *: use a custom error class for all errors thrown by owl

This commit makes all errors thrown in owl use a custom error class. The
main point of this is to always wrap user-code errors that happen during
the owl lifecycle so that they can be treated uniformly in onError by
checking the cause property, and also allows user code to differenciate
owl errors from non-owl errors reliably at runtime.

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 };
 
@@ -31,7 +32,7 @@ function parseXML(xml: string): Document {
         }
       }
     }
-    throw new Error(msg);
+    throw new OwlError(msg);
   }
   return doc;
 }
@@ -76,7 +77,7 @@ export class TemplateSet {
       if (currentAsString === newAsString) {
         return;
       }
-      throw new Error(`Template ${name} already defined with different content`);
+      throw new OwlError(`Template ${name} already defined with different content`);
     }
     this.rawTemplates[name] = template;
   }
@@ -102,7 +103,7 @@ export class TemplateSet {
           const componentName = getCurrent().component.constructor.name;
           extraInfo = ` (for component "${componentName}")`;
         } catch {}
-        throw new Error(`Missing template: "${name}"${extraInfo}`);
+        throw new OwlError(`Missing template: "${name}"${extraInfo}`);
       }
       const isFn = typeof rawTemplate === "function" && !(rawTemplate instanceof Element);
       const templateFn = isFn ? rawTemplate : this._compileTemplate(name, rawTemplate);
@@ -119,7 +120,7 @@ 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 {