title: Provider 'xx' must return a value from $get factory method
body: <p>Here is my angular service:</p>
  
  <pre><code>angular
      .module('myApp')
      .factory('partyService', function($http) {
          this.fetch = function() {
              return $http.get('/api/parties')
                          .then(function(response) {
                              return response.data;
                          });
          }
      });
  </code></pre>
  
  <p>I think this service is returning data (or an empty array // not sure)</p>
  
  <p>Then why am I geeting this error:</p>
  
  <blockquote>
    <p>Error: [$injector:undef] Provider 'partyService' must return a value from $get factory method.</p>
  </blockquote>
  
  <p><strong>Update:</strong></p>
  
  <p>If I use service instead of factory then I don't get any errors. Why so???</p>