leading indentation disappears in query editor

I noticed a while ago the following behaviour: when starting a new line the cursor appears to get stuck on the start of the line if the line contains only spaces. This only happens if indentation is set to spaces. It also only happens for lines that contain between 9 and 19 spaces. You can just hit space on an empty line to see the effect.

In the gif I:
- type the number of the current indentation level
- hit enter
- hit tab
- repeat


Start in the query editor and reproduce the issue with spaces-only lines, using indentation set to spaces and testing lines containing 9–19 spaces. Trace what happens after pressing Space, Enter, and Tab; done means the cursor no longer appears stuck at the start of these lines.

Written by the indexing model from the issue text.