Angular 没有 ChildrenOutletContexts 的提供者 (injectionError)

使用ANGLE CLI为我的应用程序生成路由模块时，我收到以下错误:

ERROR Error: No provider for ChildrenOutletContexts!
    at injectionError (core.es5.js:1169)
    at noProviderError (core.es5.js:1207)
    at ReflectiveInjector_.webpackJsonp.../../../core/@angular/core.es5.js.ReflectiveInjector_._throwOrNull (core.es5.js:2649)
    at ReflectiveInjector_.webpackJsonp.../../../core/@angular/core.es5.js.ReflectiveInjector_._getByKeyDefault (core.es5.js:2688)
    at ReflectiveInjector_.webpackJsonp.../../../core/@angular/core.es5.js.ReflectiveInjector_._getByKey (core.es5.js:2620)
    at ReflectiveInjector_.webpackJsonp.../../../core/@angular/core.es5.js.ReflectiveInjector_.get (core.es5.js:2489)
    at resolveNgModuleDep (core.es5.js:9481)
    at NgModuleRef_.webpackJsonp.../../../core/@angular/core.es5.js.NgModuleRef_.get (core.es5.js:10569)
    at resolveDep (core.es5.js:11072)
    at createClass (core.es5.js:10936)

我用Angular CLI生成了如下路由模块:

ng generate module --routing App

以下是路由模块的内容:

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { MyComponent } from './my/my.component';

const routes: Routes = [
  {
    path: '',
    component: MyComponent,
  },
];

@NgModule({
  imports: [RouterModule.forChild(routes)],
  exports: [RouterModule],
  declarations: []
})
export class AppRoutingModule { }

这是我app.component.html美元里的钱:

<div class="container" role="main">
    <router-outlet></router-outlet>
</div>

这个错误的原因是什么？