### 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
#include "editor/editor_inspector.h"
#include "editor/editor_interface.h"
#include "editor/editor_layouts_dialog.h"
#include "editor/editor_log.h"
#include "editor/editor_native_shader_source_visualizer.h"
#include "editor/editor_paths.h"
#include "editor/editor_plugin.h"
#include "editor/editor_properties.h"
#include "editor/editor_property_name_processor.h"
#include "editor/editor_quick_open.h"
#include "editor/editor_resource_preview.h"
#include "editor/editor_run.h"
#include "editor/editor_run_native.h"
#include "editor/editor_scale.h"
#include "editor/editor_settings.h"
#include "editor/editor_settings_dialog.h"
#include "editor/editor_themes.h"
#include "editor/editor_translation_parser.h"
#include "editor/editor_undo_redo_manager.h"
#include "editor/export/editor_export.h"
#include "editor/export/export_template_manager.h"
#include "editor/export/project_export.h"
#include "editor/fbx_importer_manager.h"
#include "editor/filesystem_dock.h"
#include "editor/gui/editor_file_dialog.h"
#include "editor/gui/editor_run_bar.h"
#include "editor/gui/editor_title_bar.h"
#include "editor/gui/editor_toaster.h"
#include "editor/history_dock.h"
#include "editor/import/audio_stream_import_settings.h"