我正在Ubuntu 16.04上运行Angular2 TypeScript QuickStart（https://angular.io/guide/quickstart），虽然它工作得很好，但是当我运行npm start时，我得到了一些404的.map文件：
npm start
[1] 16.10.27 14:52:45 304 GET /index.html
[1] 16.10.27 14:52:45 304 GET /styles.css
[1] 16.10.27 14:52:45 304 GET /node_modules/core-js/client/shim.min.js
[1] 16.10.27 14:52:45 304 GET /node_modules/zone.js/dist/zone.js
[1] 16.10.27 14:52:45 304 GET /node_modules/reflect-metadata/Reflect.js
[1] 16.10.27 14:52:45 304 GET /node_modules/systemjs/dist/system.src.js
[1] 16.10.27 14:52:45 304 GET /systemjs.config.js
[1] 16.10.27 14:52:46 304 GET /app/main.js
[1] 16.10.27 14:52:47 304 GET /node_modules/@angular/platform-browser- dynamic/bundles/platform-browser-dynamic.umd.js
[1] 16.10.27 14:52:47 304 GET /app/app.module.js
[1] 16.10.27 14:52:47 304 GET /node_modules/@angular/compiler/bundles /compiler.umd.js
[1] 16.10.27 14:52:47 304 GET /node_modules/@angular/core/bundles/core.umd.js
[1] 16.10.27 14:52:47 304 GET /node_modules/@angular/platform-browser/bundles/platform-browser.umd.js
[1] 16.10.27 14:52:47 304 GET /app/app.component.js
[1] 16.10.27 14:52:47 304 GET /node_modules/rxjs/Subject.js
[1] 16.10.27 14:52:47 304 GET /node_modules/rxjs/Observable.js
[1] 16.10.27 14:52:47 304 GET /node_modules/@angular/common/bundles /common.umd.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/Subscriber.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/Subscription.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/util/ObjectUnsubscribedError.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/SubjectSubscription.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/symbol/rxSubscriber.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/util/root.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/util/toSubscriber.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/symbol/observable.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/util/isFunction.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/Observer.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/util/isArray.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/util/isObject.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/util/tryCatch.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/util/errorObject.js
[1] 16.10.27 14:52:48 304 GET /node_modules/rxjs/util/UnsubscriptionError.js
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/main.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/Subject.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/Observable.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/root.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/toSubscriber.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/Subscriber.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/isFunction.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/Subscription.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/isArray.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/isObject.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/tryCatch.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/errorObject.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/UnsubscriptionError.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/Observer.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/rxSubscriber.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/observable.js.map
[1] 16.10.27 14:52:50 404 GET /node_modules/systemjs/dist/ObjectUnsubscribedError.js.map
[1] 16.10.27 14:52:51 404 GET /node_modules/systemjs/dist/SubjectSubscription.js.map
[1] 16.10.27 14:52:51 404 GET /node_modules/systemjs/dist/app.module.js.map
[1] 16.10.27 14:52:51 404 GET /node_modules/systemjs/dist/app.component.js.map
[1] 16.10.27 14:52:52 304 GET /app/app.component.html
我该如何解决这个问题？那些.map文件到底是什么？正在运行npm install将不再安装任何内容。