I can confirm this bug. I just updated to 5.0.8 and can’t use the image field anymore (neither on options pages nor anywhere else). Console gives me this:
Uncaught Error: A "url" property or function must be specified
Edit:
Did some further testing and found out that only images <=1024 pixels width are affected. If I upload an image that’s 1025 (or more) pixels wide, it works.
Maybe that helps.