### 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)

continue;
			}
			
			if (Object::cast_to<MultiNodeEdit>(object) && p.name == "MultiNodeEdit") {
				continue;
			}
			
			List<PropertyInfo>::Element *N = E_property->next();
			bool valid = true;
			while (N) {
				if (!N->get().name.begins_with("metadata/_") && N->get().usage & PROPERTY_USAGE_EDITOR && (!restrict_to_basic || (N->get().usage & PROPERTY_USAGE_EDITOR_BASIC_SETTING))) {
					break;
				}
				if (N->get().usage & PROPERTY_USAGE_CATEGORY) {
					valid = false;
					break;
				}
				N = N->next();
			}
			if (!valid) {
				continue; 
			}
			
			EditorInspectorCategory *category = memnew(EditorInspectorCategory);
			main_vbox->add_child(category);
			category_vbox = nullptr; 
			String type = p.name;
			String label = p.name;
			doc_name = p.name;