### 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 (p_editor->has_main_screen()) {
		
		
		for (int i = singleton->main_editor_buttons.size() - 1; i >= 0; i--) {
			if (p_editor->get_name() == singleton->main_editor_buttons[i]->get_text()) {
				if (singleton->main_editor_buttons[i]->is_pressed()) {
					singleton->editor_select(EDITOR_SCRIPT);
				}
				memdelete(singleton->main_editor_buttons[i]);
				singleton->main_editor_buttons.remove_at(i);
				break;
			} else {
				singleton->main_editor_buttons[i]->disconnect("pressed", callable_mp(singleton, &EditorNode::editor_select));
				singleton->main_editor_buttons[i]->connect("pressed", callable_mp(singleton, &EditorNode::editor_select).bind(i - 1));
			}
		}
		singleton->editor_table.erase(p_editor);
	}
	p_editor->make_visible(false);
	p_editor->clear();
	if (p_config_changed) {
		p_editor->disable_plugin();