### 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
pending_addons.push_back(p_addon);
				return;
			}
			show_warning(vformat(TTR("Unable to load addon script from path: '%s'. This might be due to a code error in that script.\nDisabling the addon at '%s' to prevent further errors."), script_path, addon_path));
			_remove_plugin_from_enabled(addon_path);
			return;
		}
		
		if (String(scr->get_instance_base_type()) != "EditorPlugin") {
			show_warning(vformat(TTR("Unable to load addon script from path: '%s' Base type is not EditorPlugin."), script_path));
			return;
		}
		if (!scr->is_tool()) {
			show_warning(vformat(TTR("Unable to load addon script from path: '%s' Script is not in tool mode."), script_path));
			return;
		}
	}
	EditorPlugin *ep = memnew(EditorPlugin);
	ep->set_script(scr);
	addon_name_to_plugin[addon_path] = ep;
	add_editor_plugin(ep, p_config_changed);
	_update_addon_config();
}
bool EditorNode::is_addon_plugin_enabled(const String &p_addon) const {
	if (p_addon.begins_with("res:")) {
		return addon_name_to_plugin.has(p_addon);
	}
	return addon_name_to_plugin.has("res:addons/" + p_addon + "/plugin.cfg");
}
void EditorNode::_remove_edited_scene(bool p_change_tab) {