title: Magnific Popup - Enable zoom animation when using $.magnificPopup.open
body: <p>I am able to enable the zoom animation when I pre-initialize the Magnific Popup using the syntax below.</p>
  
  <pre><code>element.find('.productImage').magnificPopup({
                  type: 'image',
                  mainClass: 'mfp-with-zoom',
                  zoom: {
                      enabled: true,
                      duration: 300, // duration of the effect, in milliseconds
                      easing: 'ease-in-out' // CSS transition
                      }
              });
  </code></pre>
  
  <p>However, there are certain places where I need to use the $.magnificPopup.open function to display an image.  However the syntax below is giving me a "JavaScript runtime error: Object doesn't support property or method 'is'" error.</p>
  
  <pre><code>element.on('click', function() {
                  $.magnificPopup.open({
                      items: {
                          src: $(this).attr('data-mfp-src')
                      },
                      type: 'image',
                      zoom: {
                          enabled: true,
                          duration: 300, // duration of the effect, in milliseconds
                          easing: 'ease-in-out' // CSS transition
                      }
                  });
              });
  </code></pre>
  
  <p>If I remove the "zoom {...}" part from the call, it works fine though but it'd be nice to have the zoom animation when the popup is opened this way.  Is it possible at all? Please advise.  Thanks!</p>