### Godot version

4.1 rc3

### System information

Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (NVIDIA; 30.0.15.1403) - Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz (8 Threads)

### Issue description

This™
![image](https://github.com/godotengine/godot/assets/2223172/cb33110f-a5b0-400a-951f-3fa425f05714)

It can still happen, but it's more difficult to trigger.

### Steps to reproduce

1. Create a new scene with a Control node
2. Add Theme to the Control
3. Open Theme Editor
4. Clear the `theme` property in Control
5. Save, with Theme Editor opened
6. Restart

### Minimal reproduction project

N/A
distraction_free->set_pressed(p_enter);
	if (p_enter) {
		if (docks_visible) {
			set_docks_visible(false);
		}
	} else {
		set_docks_visible(true);
	}
}
bool EditorNode::is_distraction_free_mode_enabled() const {
	return distraction_free->is_pressed();
}
void EditorNode::add_control_to_dock(DockSlot p_slot, Control *p_control) {
	ERR_FAIL_INDEX(p_slot, DOCK_SLOT_MAX);
	dock_slot[p_slot]->add_child(p_control);
	_update_dock_slots_visibility();
}
void EditorNode::remove_control_from_dock(Control *p_control) {