### Godot version

v4.0.beta17.mono.official [c40020513]

### System information

Window 11, Forward+, GTX 1060

### Issue description

Adding two theme variations in a row result to a  crash.

https://user-images.githubusercontent.com/93253123/217037249-1ce1d56d-beb6-4435-83ad-9f8a07fe0e96.mp4



### Steps to reproduce

1. Create a project.
2. Create a theme.
3. Double click to go in the theme editor.
4. Click on manage items buttons.
5. In the add type field type a name to add a type.
6. type another name to add a second type.
7. Crash.

### Minimal reproduction project

[ThemeVariationCrash.zip](https://github.com/godotengine/godot/files/10665863/ThemeVariationCrash.zip)

GDCLASS(EditorInspector, ScrollContainer);
	enum {
		MAX_PLUGINS = 1024
	};
	static Ref<EditorInspectorPlugin> inspector_plugins[MAX_PLUGINS];
	static int inspector_plugin_count;
	VBoxContainer *main_vbox = nullptr;
	
	HashMap<StringName, List<EditorProperty *>> editor_property_map;
	List<EditorInspectorSection *> sections;
	HashSet<StringName> pending;
	void _clear();
	Object *object = nullptr;
	
	LineEdit *search_box = nullptr;
	bool show_categories = false;
	bool hide_script = true;
	bool hide_metadata = true;
	bool use_doc_hints = false;
	EditorPropertyNameProcessor::Style property_name_style = EditorPropertyNameProcessor::STYLE_CAPITALIZED;
	bool use_filter = false;
	bool autoclear = false;
	bool use_folding = false;
	int changing;
	bool update_all_pending = false;
	bool read_only = false;
	bool keying = false;