### 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
if (EDITOR_3D < main_editor_buttons.size() && main_editor_buttons[EDITOR_3D]->is_visible()) {
		
		editor_select(EDITOR_3D);
		return;
	}
	
	
	for (int i = 0; i < main_editor_buttons.size(); i++) {
		Button *editor_button = main_editor_buttons[i];
		if (editor_button->is_visible()) {
			editor_select(i);
			return;
		}
	}
	editor_select(-1);
}
void EditorNode::_notification(int p_what) {