### 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?)
if (key_edit) {
		memdelete(key_edit);
	}
	if (multi_key_edit) {
		memdelete(multi_key_edit);
	}
}
void AnimationTrackKeyEditEditor::_time_edit_entered() {
	int key = animation->track_find_key(track, key_ofs, Animation::FIND_MODE_APPROX);
	if (key == -1) {
		return;
	}
	key_data_cache.time = animation->track_get_key_time(track, key);
	key_data_cache.transition = animation->track_get_key_transition(track, key);
	key_data_cache.value = animation->track_get_key_value(track, key);
}
void AnimationTrackKeyEditEditor::_time_edit_exited() {
	real_t new_time = spinner->get_value();
	if (use_fps) {
		real_t fps = animation->get_step();
		if (fps > 0) {
			fps = 1.0 / fps;
		}
		new_time /= fps;
	}
	if (Math::is_equal_approx(new_time, key_data_cache.time)) {
		return; 
	}
	int existing = animation->track_find_key(track, new_time, Animation::FIND_MODE_APPROX);
	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();