### Tested versions

Caused by [0d6300d269b818e6c3d3ea9cbc592480103aa6d0] Fix folder color not showing up in file dialogs
https://github.com/godotengine/godot/pull/84837
(git bisection)

### System information

Godot v4.3.dev (6faa5c6dc) - Fedora Linux 39 (Workstation Edition) - Wayland - Vulkan (Forward+) - dedicated AMD Radeon RX Vega (RADV VEGA10) () - AMD Ryzen 7 5800X 8-Core Processor (16 Threads)

### Issue description

When opening the export path, it results in a black popup.

![image](https://github.com/godotengine/godot/assets/270928/d67dee6a-f1e1-4bf3-8a3f-419554269f4a)


### Steps to reproduce

1. Open export settings
2. Add an export target
3. Try to select an export path

### Minimal reproduction project (MRP)

n/a
int thumbnail_size = EDITOR_GET("filesystem/file_dialog/thumbnail_size");
	thumbnail_size *= EDSCALE;
	Ref<Texture2D> folder_thumbnail;
	Ref<Texture2D> file_thumbnail;
	item_list->clear();
	
	item_list->get_v_scroll_bar()->set_value(0);
	if (display_mode == DISPLAY_THUMBNAILS) {
		item_list->set_max_columns(0);
		item_list->set_icon_mode(ItemList::ICON_MODE_TOP);
		item_list->set_fixed_column_width(thumbnail_size * 3 / 2);
		item_list->set_max_text_lines(2);
		item_list->set_text_overrun_behavior(TextServer::OVERRUN_TRIM_ELLIPSIS);
		item_list->set_fixed_icon_size(Size2(thumbnail_size, thumbnail_size));
		if (thumbnail_size < 64) {
			folder_thumbnail = theme_cache.folder_medium_thumbnail;
			file_thumbnail = theme_cache.file_medium_thumbnail;