3.9 Beta 1 Thumb-less images block gallery

Images that do not have any other file size then their original upload size (so without any thumbs) block the creation of a gallery. So although the media modal recognizes them and you can select them to put in a gallery, hitting ‘insert gallery’ fails silently with a Uncaught TypeError: Cannot read property 'url' of undefined error in the console and an empty post editor. I am not sure whether this was already the case before.