### 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)

return !revertable_properties.is_empty();
}
void EditorInspectorSection::property_can_revert_changed(const String &p_path, bool p_can_revert) {
	bool had_revertable_properties = has_revertable_properties();
	if (p_can_revert) {
		revertable_properties.insert(p_path);
	} else {
		revertable_properties.erase(p_path);
	}
	if (has_revertable_properties() != had_revertable_properties) {
		queue_redraw();
	}
}
void EditorInspectorSection::_bind_methods() {
	ClassDB::bind_method(D_METHOD("setup", "section", "label", "object", "bg_color", "foldable"), &EditorInspectorSection::setup);
	ClassDB::bind_method(D_METHOD("get_vbox"), &EditorInspectorSection::get_vbox);
	ClassDB::bind_method(D_METHOD("unfold"), &EditorInspectorSection::unfold);
	ClassDB::bind_method(D_METHOD("fold"), &EditorInspectorSection::fold);
}
EditorInspectorSection::EditorInspectorSection() {