### Godot version

4.0 Beta10

### System information

Ubuntu 22.04 (Tuxedo OS)

### Issue description

After importing an *.obj file as a scene, if you click on the mesh in the import settings Godot crashes.

![Screenshot from 2022-12-24 14-38-23](https://user-images.githubusercontent.com/25522325/209452619-3c0ed61b-deaa-4fb6-8ff5-5aa11ff4ed33.png)

I the above screenshot, clicking in the circled area will crash Godot.

### Steps to reproduce

Import .obj file into a project.
Select the file.
Go to import setting.
Change OBJ As Mesh to Scene.
Click Reimport.
Click Save Scenes, Re-Import, and Restart.
Once restarted, open the advanced import settings on the object.
Click the are circled in the description, or in the meshes tab.

### Minimal reproduction project

N/A

Specifically, I lack the distribution rights of the .obj files I am using.  Any .obj file should do, this happened to me on at least 4 different .obj files.
return IMPORT_SCENE;
}
static Error _parse_material_library(const String &p_path, HashMap<String, Ref<StandardMaterial3D>> &material_map, List<String> *r_missing_deps) {
	Ref<FileAccess> f = FileAccess::open(p_path, FileAccess::READ);
	ERR_FAIL_COND_V_MSG(f.is_null(), ERR_CANT_OPEN, vformat("Couldn't open MTL file '%s', it may not exist or not be readable.", p_path));
	Ref<StandardMaterial3D> current;
	String current_name;
	String base_path = p_path.get_base_dir();
	while (true) {
		String l = f->get_line().strip_edges();
		if (l.begins_with("newmtl ")) {
			
			current_name = l.replace("newmtl", "").strip_edges();
			current.instantiate();
			current->set_name(current_name);
			material_map[current_name] = current;
		} else if (l.begins_with("Ka ")) {
			
			WARN_PRINT("OBJ: Ambient light for material '" + current_name + "' is ignored in PBR");
		} else if (l.begins_with("Kd ")) {