Trying to add a gallery to a sub-page but I keep getting this JS error:

Uncaught TypeError: BigTreePhotoGallery.extend is not a function
Uncaught TypeError: CustomPhotoGallery is not a function

I'm able to add the images but when I select them and hit "use this image" chrome asks me if I'm sure I want to leave this page or if I want to stay because I have unsaved information on the page.  But there is no save button.  So it does not create a gallery array.

I was looking at the demo site and getting the same error.  I'm working with 4.2.1
Any help or suggestions would be appreciated