title: AngularJS V1.1 interceptor always have $q.when at the end
body: <p>In the <a href="https://code.angularjs.org/1.1.5/docs/api/ng.$http" rel="nofollow noreferrer">documentation</a> (version 1.1) of AngularJS about interceptors, the interceptor functions all return something like this</p>
  
  <pre><code>return response || $q.when(response);
  </code></pre>
  
  <p>However, in my app, 'response' is always defined, so $q.when(response) is never executed.
  So the question is in what situation will the 'response' be undefined and what will</p>
  
  <pre><code>$q.when(response) // == $q.when(null)
  </code></pre>
  
  <p>do! because response is undefined/null ?</p>