As I was debugging the broken alt text due to not encoding the double quotes I found these 404’s in the Firefox browser console. Perhaps the files just need creating or the code altered to check whether they exist or not.
this is just a console information saying a code mapping file is missing, it’s nothing to worry about as it won’t affect the functionality of Gallery Pro.
I will add this to our todo list to clean up though 
That’s why I called it a buglet. Probably just uninitialised variables that aren’t used but consume space on the debug screen when looking for other issues.