title: angular 2 view renders before data loads in ngOnInit
body: <p>I use github API to load user and his followers data in my angular 2 app, but view renders before ngOnInit finishes load data and because of this I receive: 
  <code>Cannot read property of undefined</code> error. My code fragment looks like this:</p>
  
  <pre><code>ngOnInit() {
      Observable.forkJoin(
          this._githubService.getUser('kaxi1993'),
          this._githubService.getFollowers('kaxi1993')
      )
      .subscribe(res =&gt; {
          this.user = res[0];
          this.followers = res[1];
      },
      null,
      () =&gt; {
          this.isLoading = false;
      });
  }
  </code></pre>
  
  <p>if I write html code like this:</p>
  
  <pre><code> &lt;div *ngIf="user &amp;&amp; user.avatar_url"&gt;
     &lt;img class="media-object avatar" [src]="user.avatar_url" alt="..."&gt;
   &lt;/div&gt;
  </code></pre>
  
  <p>works fine, but returns error <code>Cannot read property 'avatar_url' of undefined</code> when write html code without <code>*ngIf</code> like this:</p>
  
  <pre><code>&lt;img class="media-object avatar" [src]="user.avatar_url" alt="..."&gt;
  </code></pre>
  
  <p>also note: <code>getFollowers</code> works fine, but if I move 
  <code>getFollowers</code> before <code>getUsers</code> in <code>forkJoin</code> method then <code>getUsers</code> works fine and <code>getFollowers</code> need <code>*ngIf</code> to avoid error.
  Is it possible to write without extra *ngIf code? any help guys, Thanks a lot.</p>