为什么模块没有找到角度误差

Question

我在module not found error中遇到错误我已安装该模块。

这是我的代码 https://stackblitz.com/edit/angular-bup8gb

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { HttpClientModule } from '@angular/common/http'
import { DataService } from './dataservice';   // our custom service, see below
import { AppComponent } from './app.component';

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