1. Go to https://www.mediawiki.org/wiki/VisualEditor:Testy and click edit
2. Select all using Ctrl-A (or Cmd-A) and press backspace
3. Press any content key (e.g. "a")

What should happen:

: You get a document with an "a" in its own paragraph.

What does happen:

: You get a document with an "a" in its own paragraph, and a pawn.

Version: unspecified
Severity: critical