One thing that stands out is:
Exception in module-execute in module ext.gadget.CropTool: load.php:176:576
TypeError: mw.Uri is not a constructor TypeError: mw.Uri is not a constructor
Thanks! After enabling CropTool on https://commons.wikimedia.org/wiki/Special:Preferences#mw-prefsection-gadgets and going to https://commons.wikimedia.org/wiki/File:Pillangós_-_panoramio.jpg?debug=true (note the debug=true) I still cannot reproduce. :(
I have more luck reproducing it with "fresh" files. Refreshing the page will fix it, and then it stays fixed when refreshed several more times. There's nothing special about that particular file I posted, it's quite easy for me to reproduce on a random file. Adding ?debug=true seems to fix it too.
The CropTool gadget was definitely missing a dependency. Fixed: https://commons.wikimedia.org/w/index.php?title=MediaWiki:Gadgets-definition&diff=225909613&oldid=211657054
The issue was caused by this edit to the gadget: https://commons.wikimedia.org/w/index.php?title=MediaWiki:Gadget-CropTool.js&diff=203599240&oldid=118183121 (this was a while ago, I don't know why it only started causing problems now. Something else must have been loading mediawiki.Uri and now it doesn't need it, or the load order has changed.)
I'll follow up at the help desk too, that user might be having a separate problem.
@Ghouston: Your console log was very useful, thanks. Out of curiosity, it seems to also have a ton of other "errors" which really look like some sort of debugging warnings (e.g. "SyntaxError: test for equality (==) mistyped as assignment (=)?") – how do you even enable that?
Thanks, that fixes it for me. I guess the load order was changing between the working and non-working versions, maybe depending on whether the files were cached.