While editing user JavaScript pages on enwiki today, I twice got the error "Uncaught TypeError: $(...).data(...).fn.codeEditorMonitorFragment is not a function: index.php:114", on two different pages. On both of these times CodeEditor failed to load, and when I checked the second time it happened my user scripts had failed to load too. However, it was an intermittent problem - most of the time both CodeEditor and my user scripts loaded just fine.

I assume that on both times that I saw the errors some central piece of JavaScript had failed to load, although I haven't investigated what it might be. It might be that CodeEditor isn't able to run under those conditions anyway, but in that case it might be nice to have a better error message.