在localhost：3000上启动npm后，控制台显示错误

Question

点击 npm start 后，我在控制台日志中收到以下错误 在localhost：3000

无法GET / @ angular / platform-b​​rowser-dynamic

无法GET / @ angular / platform-b​​rowser-dynamic

npm版本3.10.9 节点版本v7.2.0

package.json如下

{
  "name": "angular-quickstart",
  "version": "1.0.0",
  "description": "QuickStart package.json from the documentation, supplemented with testing support",
  "scripts": {
    "build": "tsc -p src/",
    "build:watch": "tsc -p src/ -w",
    "build:e2e": "tsc -p e2e/",
    "serve": "lite-server -c=bs-config.json",
    "serve:e2e": "lite-server -c=bs-config.e2e.json",
    "prestart": "npm run build",
    "start": "concurrently \"npm run build:watch\" \"npm run serve\"",
    "pree2e": "npm run build:e2e",
    "e2e": "concurrently \"npm run serve:e2e\" \"npm run protractor\" --kill-others --success first",
    "preprotractor": "webdriver-manager update",
    "protractor": "protractor protractor.config.js",
    "pretest": "npm run build",
    "test": "concurrently \"npm run build:watch\" \"karma start karma.conf.js\"",
    "pretest:once": "npm run build",
    "test:once": "karma start karma.conf.js --single-run",
    "lint": "tslint ./src/**/*.ts -t verbose"
  },
  "keywords": [],
  "author": "",
  "license": "MIT",
  "dependencies": {
    "@angular/common": "~4.0.0",
    "@angular/compiler": "~4.0.0",
    "@angular/core": "~4.0.0",
    "@angular/forms": "~4.0.0",
    "@angular/http": "~4.0.0",
    "@angular/material": "^2.0.0-beta.3",
    "@angular/platform-browser": "~4.0.0",
    "@angular/platform-browser-dynamic": "~4.1.3",
    "@angular/router": "~4.0.0",
    "angular-in-memory-web-api": "~0.3.0",
    "core-js": "^2.4.1",
    "rxjs": "5.0.1",
    "systemjs": "0.19.40",
    "zone.js": "^0.8.4"
  },
  "devDependencies": {
    "concurrently": "^3.2.0",
    "lite-server": "^2.2.2",
    "typescript": "~2.1.0",
    "canonical-path": "0.0.2",
    "tslint": "^3.15.1",
    "lodash": "^4.16.4",
    "jasmine-core": "~2.4.1",
    "karma": "^1.3.0",
    "karma-chrome-launcher": "^2.0.0",
    "karma-cli": "^1.0.1",
    "karma-jasmine": "^1.0.2",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~4.0.14",
    "rimraf": "^2.5.4",
    "@types/node": "^6.0.46",
    "@types/jasmine": "2.5.36"
  },
  "repository": {}
}

app.module.ts如下

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
 import { MaterialModule } from '@angular/material';
import { AppComponent }  from './app.component';

@NgModule({
  imports:      [ BrowserModule, MaterialModule ],
  declarations: [ AppComponent ],
  bootstrap:    [ AppComponent ]
})
export class AppModule { }

Main.ts

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';

import { AppModule } from './app/app.module';

platformBrowserDynamic().bootstrapModule(AppModule);

为什么应用程序无法在node_modules下加载platform-b​​rowser-dynamic？我验证了文件存在于指定的文件夹下，但我仍然收到此错误。