Почему я получаю ошибку при загрузке RxJS-расширений в Angular 2?

я следил за туром героев учебник на сайте angular2 шаг за шагом, но я наткнулся на небольшую загвоздку, когда я попал в раздел http учебника. Почему я продолжаю получать эти ошибки в консоли?

" GET http://localhost:3000/app/rxjs-extensions.js 404 (Не Найдено)"

и

" ошибка: ошибка: ошибка XHR (404 не найдено) загрузка http://localhost:3000/app/rxjs-extensions.js(...)"

это мой systemjs.config.js:

(function(global) {
  // map tells the System loader where to look for things
  var map = {
    'app':                        'app', // 'dist',
    '@angular':                   'node_modules/@angular',
    'angular2-in-memory-web-api': 'node_modules/angular2-in-memory-web-api',
    'rxjs':                       'node_modules/rxjs'
  };
  // packages tells the System loader how to load when no filename and/or no extension
  var packages = {
    'app':                        { main: 'main.js',  defaultExtension: 'js' },
    'rxjs':                       { defaultExtension: 'js' },
    'angular2-in-memory-web-api': { main: 'index.js', defaultExtension: 'js' },
  };
  var ngPackageNames = [
    'common',
    'compiler',
    'core',
    'forms',
    'http',
    'platform-browser',
    'platform-browser-dynamic',
    'router',
    'router-deprecated',
    'upgrade',
  ];
  // Individual files (~300 requests):
  function packIndex(pkgName) {
    packages['@angular/'+pkgName] = { main: 'index.js', defaultExtension: 'js' };
  }
  // Bundled (~40 requests):
  function packUmd(pkgName) {
    packages['@angular/'+pkgName] = { main: '/bundles/' + pkgName + '.umd.js', defaultExtension: 'js' };
  }
  // Most environments should use UMD; some (Karma) need the individual index files
  var setPackageConfig = System.packageWithIndex ? packIndex : packUmd;
  // Add package entries for angular packages
  ngPackageNames.forEach(setPackageConfig);
  var config = {
    map: map,
    packages: packages
  };
  System.config(config);
})(this);

мой app.module.ts:

import { NgModule }       from '@angular/core';
import { BrowserModule }  from '@angular/platform-browser';
import { FormsModule }    from '@angular/forms';
// Imports for loading & configuring the in-memory web api
import { HttpModule, XHRBackend } from '@angular/http';
import { InMemoryBackendService, SEED_DATA } from 'angular2-in-memory-web-api';
import { InMemoryDataService }               from './in-memory-data.service';
import { AppComponent }   from './app.component';
import { routing }        from './app.routing';
import { HeroesComponent }      from './heroes.component';
import { DashboardComponent }   from './dashboard.component';
import { HeroDetailComponent }  from './hero-detail.component';
import { HeroSearchComponent }  from './hero-search.component';
import { HeroService }  from './hero.service';

@NgModule({
    imports: [
        BrowserModule,
        FormsModule,
        routing,
        HttpModule
    ],
    declarations: [
        AppComponent,
        HeroesComponent,
        DashboardComponent,
        HeroDetailComponent,
        HeroSearchComponent
    ],
    providers: [
        HeroService,
        { provide: XHRBackend, useClass: InMemoryBackendService }, // in-mem server
        { provide: SEED_DATA,  useClass: InMemoryDataService }     // in-mem server data
    ],
    bootstrap: [ AppComponent ]
})
export class AppModule {
}

мой hero.service.ts:

import { Injectable }    from '@angular/core';
import { Headers, Http } from '@angular/http';
import 'rxjs/add/operator/toPromise';
import { Hero } from './hero';


@Injectable()
export class HeroService {
    private heroesUrl = 'app/heroes';  // URL to web api
    constructor(private http: Http) { }
    getHeroes() {
        return this.http.get(this.heroesUrl)
            .toPromise()
            .then(response => response.json().data as Hero[])
            .catch(this.handleError);
    }
    getHero(id: number) {
        return this.getHeroes()
            .then(heroes => heroes.find(hero => hero.id === id));
    }
    save(hero: Hero): Promise<Hero>  {
        if (hero.id) {
            return this.put(hero);
        }
        return this.post(hero);
    }
    delete(hero: Hero) {
        let headers = new Headers();
        headers.append('Content-Type', 'application/json');
        let url = `${this.heroesUrl}/${hero.id}`;
        return this.http
            .delete(url, {headers: headers})
            .toPromise()
            .catch(this.handleError);
    }
    // Add new Hero
    private post(hero: Hero): Promise<Hero> {
        let headers = new Headers({
            'Content-Type': 'application/json'});
        return this.http
            .post(this.heroesUrl, JSON.stringify(hero), {headers: headers})
            .toPromise()
            .then(res => res.json().data)
            .catch(this.handleError);
    }
    // Update existing Hero
    private put(hero: Hero) {
        let headers = new Headers();
        headers.append('Content-Type', 'application/json');
        let url = `${this.heroesUrl}/${hero.id}`;
        return this.http
            .put(url, JSON.stringify(hero), {headers: headers})
            .toPromise()
            .then(() => hero)
            .catch(this.handleError);
    }
    private handleError(error: any) {
        console.error('An error occurred', error);
        return Promise.reject(error.message || error);
    }
}

мой hero-search.component.ts:

import { Component, OnInit } from '@angular/core';
import { Router }            from '@angular/router';
import { Observable }        from 'rxjs/Observable';
import { Subject }           from 'rxjs/Subject';
import { HeroSearchService } from './hero-search.service';
import { Hero } from './hero';

@Component({
    selector: 'hero-search',
    templateUrl: 'app/hero-search.component.html',
    styleUrls:  ['app/hero-search.component.css'],
    providers: [HeroSearchService]
})
export class HeroSearchComponent implements OnInit {
    heroes: Observable<Hero[]>;
    private searchTerms = new Subject<string>();
    constructor(
        private heroSearchService: HeroSearchService,
        private router: Router) {}
    // Push a search term into the observable stream.
    search(term: string) { this.searchTerms.next(term); }
    ngOnInit() {
        this.heroes = this.searchTerms
            .debounceTime(300)        // wait for 300ms pause in events
            .distinctUntilChanged()   // ignore if next search term is same as previous
            .switchMap(term => term   // switch to new observable each time
                // return the http search observable
                ? this.heroSearchService.search(term)
                // or the observable of empty heroes if no search term
                : Observable.of<Hero[]>([]))
            .catch(error => {
                // TODO: real error handling
                console.log(error);
                return Observable.of<Hero[]>([]);
            });
    }
    gotoDetail(hero: Hero) {
        let link = ['/detail', hero.id];
        this.router.navigate(link);
    }
}

мой main.ts:

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { AppModule } from './app.module';
import "rxjs/Rx";

platformBrowserDynamic().bootstrapModule(AppModule);

и index.html:

<html>
  <head>
    <base href="/">
    <title>Angular 2 QuickStart</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="styles.css">
    <!-- 1. Load libraries -->
     <!-- Polyfill(s) for older browsers -->
    <script src="node_modules/core-js/client/shim.min.js"></script>
    <script src="node_modules/zone.js/dist/zone.js"></script>
    <script src="node_modules/reflect-metadata/Reflect.js"></script>
    <script src="node_modules/systemjs/dist/system.src.js"></script>
    <!-- 2. Configure SystemJS -->
    <script src="systemjs.config.js"></script>
    <script>
      System.import('app').catch(function(err){ console.error(err); });
    </script>
  </head>
  <!-- 3. Display the application -->
  <body>
    <my-app>Loading...</my-app>
  </body>
</html>