### 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?)
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() {