Regarding the following page: admin/appearance/settings/md_springspray -> Display -> Photogallery

When I click the "Choose Image" button on any gallery-entry, nothing happens and the console reads:

TypeError: Drupal.media is undefined - script.js:387:21

The code which generates the exception is:

function selectMedia() {
                $(document).on('click', ".select-media",function(event){
                    clickMedia = $(this);
                    Drupal.media.popups.mediaBrowser(chooseBackground);  <------------------------ THIS LINE
                    event.preventDefault();
                })
            }

This problem was first encountered after updating Drupal and it's modules.

How can I fix this?