[FIX] runtime: properly handle error caused in mounted hook

If a component onMounted hook causes an error, and an error handler
tries to reinitiate a new correct render, the fiber may be recycled. But
the scheduler removes it from its own set of tasks, so it will be
ignored.

We simply check for this condition before removing it from the tasks
set.

tests/components/error_handling.test.ts

@@ -564,6 +564,82 @@ describe("can catch errors", () => {
     expect(mockConsoleWarn).toBeCalledTimes(0);
   });
 
+  test("can catch an error in onmounted", async () => {
+    class ErrorComponent extends Component {
+      static template = xml`<div>Error!!!</div>`;
+      setup() {
+        useLogLifecycle();
+        onMounted(() => {
+          throw new Error("error");
+        });
+      }
+    }
+    class PerfectComponent extends Component {
+      static template = xml`<div>perfect</div>`;
+      setup() {
+        useLogLifecycle();
+      }
+    }
+    class Main extends Component {
+      static template = xml`Main<t t-if="state.ok" t-component="component"/>`;
+      component: any;
+      state: any;
+      setup() {
+        this.state = useState({ ok: false });
+        useLogLifecycle();
+        this.component = ErrorComponent;
+        onError(() => {
+          this.component = PerfectComponent;
+          this.render();
+        });
+      }
+    }
+
+    const app = await mount(Main, fixture);
+    expect(steps.splice(0)).toMatchInlineSnapshot(`
+      Array [
+        "Main:setup",
+        "Main:willStart",
+        "Main:willRender",
+        "Main:rendered",
+        "Main:mounted",
+      ]
+    `);
+    expect(fixture.innerHTML).toBe("Main");
+    (app as any).state.ok = true;
+    await nextTick();
+    expect(fixture.innerHTML).toBe("Main<div>Error!!!</div>");
+    expect(steps.splice(0)).toMatchInlineSnapshot(`
+      Array [
+        "Main:willRender",
+        "ErrorComponent:setup",
+        "ErrorComponent:willStart",
+        "Main:rendered",
+        "ErrorComponent:willRender",
+        "ErrorComponent:rendered",
+        "Main:willPatch",
+        "ErrorComponent:mounted",
+        "Main:willRender",
+        "PerfectComponent:setup",
+        "PerfectComponent:willStart",
+        "Main:rendered",
+      ]
+    `);
+    await nextTick();
+    expect(steps.splice(0)).toMatchInlineSnapshot(`
+      Array [
+        "PerfectComponent:willRender",
+        "PerfectComponent:rendered",
+        "Main:willPatch",
+        "ErrorComponent:willUnmount",
+        "ErrorComponent:willDestroy",
+        "PerfectComponent:mounted",
+        "Main:patched",
+      ]
+    `);
+    expect(fixture.innerHTML).toBe("Main<div>perfect</div>");
+  });
+
   test("calling a hook outside setup should crash", async () => {
     class Root extends Component {
       static template = xml`<t t-esc="state.value"/>`;