Angular 中添加 ＜router-outlet＞ 标签后报错

1. If ‘router-outlet’ is an Angular component, then verify that it is part of this module.
2. If ‘router-outlet’ is a Web Component then add ‘CUSTOM_ELEMENTS_SCHEMA’ to the ‘@NgModule.schemas’ of this component to suppress this message.

app-routing.module
@NgModule({
  declarations: [],
  imports: [
    CommonModule,
    RouterModule.forRoot(
      appRoutes,
      { enableTracing: true }
    )
  ],
  exports: [ RouterModule ] // 在此处需要做导出
})