FiledColour colour picker keyboard nav gets stuck in the top left

[microbit-matt-hillsdon]

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• I have searched for similar issues before opening a new one.

Component

@blockly/field-colour

Description

If you navigate to the top left further arrow key navigation doesn't work so you get stuck on white (no logged error).

Reproduction steps

1. Run npm start in plugins/field-colour
   • I had to downgrade @blockly/dev-tools as the referenced 8.0.13 isn't in NPM - maybe due to this bug)
2. Drag a block with a colour picker
3. Click on the picker
4. Navigate to top left with the arrow keys
5. Notice you can't navigate anymore
   Happens regardless of whether left or up arrow took you to the top left. Maybe something awry in this code.

Stack trace

Screenshots

[cpcallen]

I can confirm this (and also that it can be reproduce on the demo page for field-colour).