Crash by switching between Advanced and Custom workspaces

Current 3.0 dev. f4471d2 / Windows10

- Since the palettes are involved, and to be sure to be able to reproduce, it is preferable to first revert to the factory settings.

Then:

1) "Untitled" score
2) From Advanced workspace: create a Custom workspace -> Ok
3) Switch to Advanced workspace
4) Switch to Custom workspace
5) Toggle one last time for Advanced workspace

Result: crash

It is possible that this is related (same root cause?) to this issue: #229336: Deletion of a palette leads to crash after reload the program
But as I do not really know, I prefer to fill this report.