### 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
FileSystemDock::FileListDisplayMode dock_filesystem_file_list_display_mode = FileSystemDock::FileListDisplayMode(int(p_layout->get_value(p_section, "dock_filesystem_file_list_display_mode")));
		FileSystemDock::get_singleton()->set_file_list_display_mode(dock_filesystem_file_list_display_mode);
	}
	if (p_layout->has_section_key(p_section, "dock_filesystem_selected_paths")) {
		PackedStringArray dock_filesystem_selected_paths = p_layout->get_value(p_section, "dock_filesystem_selected_paths");
		for (int i = 0; i < dock_filesystem_selected_paths.size(); i++) {
			FileSystemDock::get_singleton()->select_file(dock_filesystem_selected_paths[i]);
		}
	}
	
	PackedStringArray uncollapsed_tis;
	if (p_layout->has_section_key(p_section, "dock_filesystem_uncollapsed_paths")) {
		uncollapsed_tis = p_layout->get_value(p_section, "dock_filesystem_uncollapsed_paths");
	} else {
		uncollapsed_tis = { "res:" };
	}
	if (!uncollapsed_tis.is_empty()) {
		for (int i = 0; i < uncollapsed_tis.size(); i++) {
			TreeItem *uncollapsed_ti = FileSystemDock::get_singleton()->get_tree_control()->get_item_with_metadata(uncollapsed_tis[i], 0);
			if (uncollapsed_ti) {
				uncollapsed_ti->set_collapsed(false);
			}
		}
		FileSystemDock::get_singleton()->get_tree_control()->queue_redraw();
	}
}
void EditorNode::_save_central_editor_layout_to_config(Ref<ConfigFile> p_config_file) {
	
	int center_split_offset = center_split->get_split_offset();
	p_config_file->set_value(EDITOR_NODE_CONFIG_SECTION, "center_split_offset", center_split_offset);