### Godot version

4.0.rc

### System information

Any

### Issue description

If the RESET animation is generated at the same time as the Bezier track is generated, the bezier edit button will not be active.

![image](https://user-images.githubusercontent.com/61938263/218256176-88b1b196-7b6b-4404-84ad-e8694f23bb1b.png)

Also, if you delete a track in the Bezier Editor, or in undo redo, it will not update correctly.

### Steps to reproduce

![image](https://user-images.githubusercontent.com/61938263/218256230-4b0219d5-87e4-453a-8294-59f8feb0cfd5.png)


### Minimal reproduction project

N/A
timeline->set_use_fps(p_mode == 1);
	if (key_edit) {
		key_edit->set_use_fps(p_mode == 1);
	}
	_update_step_spinbox();
}
void AnimationTrackEditor::_update_step_spinbox() {
	if (!animation.is_valid()) {
		return;
	}
	step->set_block_signals(true);
	if (timeline->is_using_fps()) {
		if (animation->get_step() == 0) {
			step->set_value(0);
		} else {
			step->set_value(1.0 / animation->get_step());
		}
	} else {
		step->set_value(animation->get_step());
	}
	step->set_block_signals(false);
}
void AnimationTrackEditor::_animation_update() {