Steps to reproduce:
- Open Code Editor
- Select a language
- Without typing in anything in the editor, click on the Insert button
- Observe the "Save page" button also got enabled on the page
- If you now look at the diff view, you will see there have been no changes but still, you will be able to save the page.
This bug seems to exist in production too, but I see one tiny difference in the way it shows in wikitext view. In Beta and test2 it just says "no changes" but in en.wiki it shows an empty line has been added.
Diff view in test2 and Beta:
Diff view in en.wiki: