### 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
for (int i = 0; i < bottom_panel_items.size(); i++) {
		if (bottom_panel_items[i].control->is_visible()) {
			_bottom_panel_switch(false, i);
			break;
		}
	}
}
void EditorNode::make_bottom_panel_item_visible(Control *p_item) {
	for (int i = 0; i < bottom_panel_items.size(); i++) {
		if (bottom_panel_items[i].control == p_item) {
			_bottom_panel_switch(true, i);
			break;
		}
	}
}
void EditorNode::raise_bottom_panel_item(Control *p_item) {
	for (int i = 0; i < bottom_panel_items.size(); i++) {
		if (bottom_panel_items[i].control == p_item) {
			bottom_panel_items[i].button->move_to_front();
			SWAP(bottom_panel_items.write[i], bottom_panel_items.write[bottom_panel_items.size() - 1]);
			break;
		}
	}
	for (int i = 0; i < bottom_panel_items.size(); i++) {
		bottom_panel_items[i].button->disconnect("toggled", callable_mp(this, &EditorNode::_bottom_panel_switch));
		bottom_panel_items[i].button->connect("toggled", callable_mp(this, &EditorNode::_bottom_panel_switch).bind(i));
	}
}
void EditorNode::remove_bottom_panel_item(Control *p_item) {