fix: error option in async component migration page (#759)

Co-authored-by: 黄百途 <[email protected]>

Author: lovetingyuan

src/guide/migration/async-components.md

@@ -66,8 +66,8 @@ const asyncPageWithOptions = defineAsyncComponent({
   loader: () => import('./NextPage.vue'),
   delay: 200,
   timeout: 3000,
-  error: ErrorComponent,
-  loading: LoadingComponent
+  errorComponent: ErrorComponent,
+  loadingComponent: LoadingComponent
 })
 ```