### Godot version

4.0.dev (c309de53997feff3286295fb2d71657f112a15db)

### System information

Linux, Nvidia, Vulkan

### Issue description

Editor segfaults when certain conditions are met when using the AnimationPlayer editor.

### Steps to reproduce

1. Create multiple animations, saved into a animation collection
2. Open an existing animation, then make a new empty animation
3. Change from seconds to fps, or add a new property to animate ()
4. Editor crashes

NOTE: It is slightly random and I have not found a perfect repro

### Minimal reproduction project

N/A (TBD?)
sk.track = E->key().track;
		if (selection.has(sk)) {
			continue; 
		}
		undo_redo->add_do_method(animation.ptr(), "track_remove_key_at_time", E->key().track, newtime);
		_AnimMoveRestore amr;
		amr.key = animation->track_get_key_value(E->key().track, idx);
		amr.track = E->key().track;
		amr.time = newtime;
		amr.transition = animation->track_get_key_transition(E->key().track, idx);
		to_restore.push_back(amr);
	}
	
	for (RBMap<SelectedKey, KeyInfo>::Element *E = selection.back(); E; E = E->prev()) {
		float newpos = snap_time(E->get().pos + motion);
		undo_redo->add_do_method(animation.ptr(), "track_insert_key", E->key().track, newpos, animation->track_get_key_value(E->key().track, E->key().key), animation->track_get_key_transition(E->key().track, E->key().key));
	}
	
	for (RBMap<SelectedKey, KeyInfo>::Element *E = selection.back(); E; E = E->prev()) {
		float newpos = snap_time(E->get().pos + motion);
		undo_redo->add_undo_method(animation.ptr(), "track_remove_key_at_time", E->key().track, newpos);
	}
	
	for (RBMap<SelectedKey, KeyInfo>::Element *E = selection.back(); E; E = E->prev()) {
		undo_redo->add_undo_method(animation.ptr(), "track_insert_key", E->key().track, E->get().pos, animation->track_get_key_value(E->key().track, E->key().key), animation->track_get_key_transition(E->key().track, E->key().key));
	}
	
	for (_AnimMoveRestore &amr : to_restore) {
		undo_redo->add_undo_method(animation.ptr(), "track_insert_key", amr.track, amr.time, amr.key, amr.transition);
	}