命名空间没有导出成员“User”Angularfire 2

Question

服务档案：

import { Injectable } from '@angular/core';
import {AngularFireAuth} from 'angularfire2/auth';
import {Observable} from 'rxjs/Observable';
import * as firebase from 'firebase/app';


@Injectable()
export class AfService {
  user: Observable<firebase.User>;
  constructor(public afAuth : AngularFireAuth){
    this.user=afAuth.authState;
  }

  loginWithGoogle(){
    const provider= new firebase.auth.GoogleAuthProvider();
    this.afAuth.auth.signInWithPopup(provider);

  }
  logout(){
    this.afAuth.auth.signOut();
  }

}

app.module：

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import {AngularFireModule} from 'angularfire2';
import {AngularFireDatabaseModule,AngularFireDatabase} from 'angularfire2/database';

import {AppRoutingModule} from './app-routing-module';
import { AppComponent } from './app.component';
import {environment} from '../environments/environment';
import { PagesListComponent } from './pages-list/pages-list.component';
import { LoginPageComponent } from './login-page/login-page.component';
import {AfService} from './providers/af.service';
import {AngularFireAuthModule} from 'angularfire2/auth';
@NgModule({
  declarations: [
    AppComponent,
    PagesListComponent,
    LoginPageComponent,

  ],
  imports: [
    BrowserModule,
    AngularFireModule.initializeApp(environment.firebase),
    AngularFireDatabaseModule,
    AppRoutingModule,
    AngularFireAuthModule
  ],
  providers: [AfService],
  bootstrap: [AppComponent]
})
export class AppModule { }

编译时出错 -

*******命名空间'“/ Users / Triathlon / Desktop / cms / cms-app / node_modules / firebase / app / index”'没有导出的成员'User'。

属性'auth'在类型'typeof“/ Users / Triathlon / Desktop / cms / cms-app / node_modules / firebase / app / index”'上不存在。**