title: How to catch error in Observable.forkJoin(...)?
body: <p>I use <code>Observable.forkJoin()</code> to handle the response after both HTTP calls finishes, but if either one of them returns an error, how can I catch that error?</p>
  
  <pre><code>Observable.forkJoin(
    this.http.post&lt;any[]&gt;(URL, jsonBody1, postJson) .map((res) =&gt; res),
    this.http.post&lt;any[]&gt;(URL, jsonBody2, postJson) .map((res) =&gt; res)
  )
  .subscribe(res =&gt; this.handleResponse(res))
  </code></pre>