Topic on Extension talk:CodeEditor/Flow

I've found out — it was all about Gadget, not this extension!

Pressing button "Edit" on [kinda] any page with CodeEditor enabled lead me to page with damaged view, where there are coloured spots above with no code (in front of big white square) and the code is below (in a window).

MW 1.39.1. I've updated all dependencies via Composer. Can anybody suggest the reason?

Probably, it's not CodeEditor, because problem repeats after its disabling.