title: Error: No Firebase App '[DEFAULT]' has been created
body: <p>I'm using Ionic2 and when I go to localhost:8100 (after doing <code>ionic serve</code>) I receive the error you can see in the following image. </p>
  
  <p><a href="https://i.stack.imgur.com/ddJDN.png" rel="noreferrer"><img src="https://i.stack.imgur.com/ddJDN.png" alt="enter image description here"></a></p>
  
  <p><strong>app.component.ts</strong> looks like this:</p>
  
  <pre><code>import firebase from 'firebase';
  import { Component } from '@angular/core';
  import { Platform } from 'ionic-angular';
  import { StatusBar } from 'ionic-native';
  import { HomePage } from '../pages/home/home';
  
  @Component({
    template: `&lt;ion-nav [root]="rootPage"&gt;&lt;/ion-nav&gt;`
  })
  export class MyApp {
    rootPage = HomePage;
  
    constructor(platform: Platform) {
      platform.ready().then(() =&gt; {
  
  
        var config = {
          apiKey: ".....",
          authDomain: "......",
          databaseURL: ".....",
          storageBucket: ".....",
          messagingSenderId: "......"
        };
  
        firebase.initializeApp(config);
        StatusBar.styleDefault();
      });
    }
  }
  </code></pre>
  
  <p><strong>app.module.ts</strong></p>
  
  <pre><code>import { NgModule } from '@angular/core';
  import { IonicApp, IonicModule } from 'ionic-angular';
  import { MyApp } from './app.component';
  import { HomePage } from '../pages/home/home';
  
  @NgModule({
    declarations: [
      MyApp,
      HomePage
    ],
    imports: [
      IonicModule.forRoot(MyApp)
    ],
    bootstrap: [IonicApp],
    entryComponents: [
      MyApp,
      HomePage 
    ],
    providers: []
  })
  export class AppModule {}
  </code></pre>
  
  <p><strong>My system information:</strong></p>
  
  <p>Cordova CLI: 6.3.1</p>
  
  <p>Ionic Framework Version: 2.0.0-rc.1</p>
  
  <p>Ionic CLI Version: 2.1.1</p>
  
  <p>Ionic App Lib Version: 2.1.1</p>
  
  <p>Ionic App Scripts Version: 0.0.36</p>
  
  <p>OS: Distributor ID: Ubuntu Description: Ubuntu 16.04.1 LTS </p>
  
  <p>Node Version: v4.2.6</p>