### 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
DisplayServer::get_singleton()->clipboard_set(warning->get_text());
}
void EditorNode::_dock_floating_close_request(WindowWrapper *p_wrapper) {
	int dock_slot_num = p_wrapper->get_meta("dock_slot");
	int dock_slot_index = p_wrapper->get_meta("dock_index");
	
	Control *dock = p_wrapper->release_wrapped_control();
	dock_slot[dock_slot_num]->add_child(dock);
	dock_slot[dock_slot_num]->move_child(dock, MIN(dock_slot_index, dock_slot[dock_slot_num]->get_tab_count()));
	dock_slot[dock_slot_num]->set_current_tab(dock_slot_index);
	floating_docks.erase(p_wrapper);
	p_wrapper->queue_free();
	_update_dock_containers();
	_edit_current();
}
void EditorNode::_dock_make_selected_float() {
	Control *dock = dock_slot[dock_popup_selected_idx]->get_current_tab_control();
	_dock_make_float(dock, dock_popup_selected_idx);
	dock_select_popup->hide();
	_edit_current();
}
void EditorNode::_dock_make_float(Control *p_dock, int p_slot_index, bool p_show_window) {