Undo/redo was crashing & asserting.
There ware two bugs:
- Entering particle system edit-mode requires an evaluated depsgraph.
- The active object could get out of sync when undo/redo
moves between different modes.
The new test 'view3d_mesh_particle_edit_mode_simple'
in `tests/ui_simulate/test_undo.py` exposes both issues.
9059ee81ef