### 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
if (display_mode == DISPLAY_LIST || p_preview.is_null()) {
		return;
	}
	for (int i = 0; i < item_list->get_item_count(); i++) {
		Dictionary d = item_list->get_item_metadata(i);
		String pname = d["path"];
		if (pname == p_path) {
			item_list->set_item_icon(i, p_preview);
			item_list->set_item_tag_icon(i, Ref<Texture2D>());
		}
	}
}
void EditorFileDialog::_thumbnail_done(const String &p_path, const Ref<Texture2D> &p_preview, const Ref<Texture2D> &p_small_preview, const Variant &p_udata) {