### 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)

_move_element(-1, -1);
}
void EditorInspectorArray::_paginator_page_changed(int p_page) {
	emit_signal("page_change_request", p_page);
}
void EditorInspectorArray::_rmb_popup_id_pressed(int p_id) {
	switch (p_id) {
		case OPTION_MOVE_UP:
			if (popup_array_index_pressed > 0) {
				_move_element(popup_array_index_pressed, popup_array_index_pressed - 1);
			}
			break;
		case OPTION_MOVE_DOWN:
			if (popup_array_index_pressed < count - 1) {
				_move_element(popup_array_index_pressed, popup_array_index_pressed + 2);
			}
			break;
		case OPTION_NEW_BEFORE:
			_move_element(-1, popup_array_index_pressed);
			break;
		case OPTION_NEW_AFTER:
			_move_element(-1, popup_array_index_pressed + 1);
			break;
		case OPTION_REMOVE:
			_move_element(popup_array_index_pressed, -1);
			break;
		case OPTION_CLEAR_ARRAY:
			_clear_array();
			break;
		case OPTION_RESIZE_ARRAY: