fix(runtime-core/async-component): fix error component when there are no error handlers

fix #2129

packages/runtime-core/__tests__/apiAsyncComponent.spec.ts

@@ -206,6 +206,51 @@ describe('api: defineAsyncComponent', () => {
     expect(serializeInner(root)).toBe('resolved')
   })
 
+  // #2129
+  test('error with error component, without global handler', async () => {
+    let resolve: (comp: Component) => void
+    let reject: (e: Error) => void
+    const Foo = defineAsyncComponent({
+      loader: () =>
+        new Promise((_resolve, _reject) => {
+          resolve = _resolve as any
+          reject = _reject
+        }),
+      errorComponent: (props: { error: Error }) => props.error.message
+    })
+
+    const toggle = ref(true)
+    const root = nodeOps.createElement('div')
+    const app = createApp({
+      render: () => (toggle.value ? h(Foo) : null)
+    })
+
+    app.mount(root)
+    expect(serializeInner(root)).toBe('<!---->')
+
+    const err = new Error('errored out')
+    reject!(err)
+    await timeout()
+    expect(serializeInner(root)).toBe('errored out')
+    expect(
+      'Unhandled error during execution of async component loader'
+    ).toHaveBeenWarned()
+
+    toggle.value = false
+    await nextTick()
+    expect(serializeInner(root)).toBe('<!---->')
+
+    // errored out on previous load, toggle and mock success this time
+    toggle.value = true
+    await nextTick()
+    expect(serializeInner(root)).toBe('<!---->')
+
+    // should render this time
+    resolve!(() => 'resolved')
+    await timeout()
+    expect(serializeInner(root)).toBe('resolved')
+  })
+
   test('error with error + loading components', async () => {
     let resolve: (comp: Component) => void
     let reject: (e: Error) => void