While the previous fix for T84920 is correct, the crash could still be
triggered by changing the active object while in edit-mode.
Ensure stale data isn't used by tagging for depsgraph update when
edit-mode data is freed on undo.
While exiting edit-mode normally does this, it's possible to set the
active object to a non edit-mode mesh, skipping the mode-switch
operator and it's depsgraph tagging.