[IMP] component: re-introduce error handling in lifecycle

src/component/error_handling.ts

@@ -0,0 +1,50 @@
+import type { ComponentNode } from "./component_node";
+import type { Fiber } from "./fibers";
+
+export const fibersInError: WeakMap<Fiber, Error> = new WeakMap();
+export const nodeErrorHandlers: WeakMap<ComponentNode, ((error: Error) => void)[]> = new WeakMap();
+
+function _handleError(node: ComponentNode | null, error: Error): boolean {
+  if (!node) {
+    return false;
+  }
+  const fiber = node.fiber;
+  if (fiber) {
+    fibersInError.set(fiber, error);
+  }
+
+  const errorHandlers = nodeErrorHandlers.get(node);
+  if (errorHandlers) {
+    if (fiber && !fiber.children.length) {
+      fiber.root.counter--;
+    }
+
+    let propagate = true;
+    for (const h of errorHandlers) {
+      try {
+        h(error);
+        propagate = false;
+      } catch (e) {
+        error = e as Error;
+      }
+    }
+
+    if (propagate) {
+      return _handleError(node.parent, error);
+    }
+    return true;
+  } else {
+    return _handleError(node.parent, error);
+  }
+}
+
+export function handleError(node: ComponentNode, error: Error) {
+  const fiber = node.fiber!;
+  fibersInError.set(fiber.root, error);
+
+  if (!_handleError(node, error)) {
+    try {
+      node.app.destroy();
+    } catch (e) {}
+  }
+}