### Godot version

4.0 RC1

### System information

Linux Mint 20.3 Cinnamon

### Issue description

Tried converting a 3.5 game to 4.0 RC1. The conversion popup menu closed after a few seconds, and trying to edit the game crashes the entire engine with the following errors, which seem to be related to one music file not loading:
![errors](https://user-images.githubusercontent.com/125468288/219127087-f5a78035-4e4a-4625-aadb-e0cde6d5ac3d.png)

Not sure what's causing the issue, because when I created a new project with only that file and converted it I didn't get these errors, but consistently get them when trying to convert that game.

### Steps to reproduce

- Download the reproduction project below
- Import in Godot 4.0, and click "convert full project"
- If the bug happens, the engine will crash whenever trying to edit or run the converted project

### Minimal reproduction project

[Music Convertor Crash Demo.zip](https://github.com/godotengine/godot/files/10746591/Music.Convertor.Crash.Demo.zip)

if (changed_elements.size() > 0 && !is_ignored) {
			converted_files++;
			for (int k = 0; k < changed_elements.size(); k++) {
				print_line(String("\t\t") + changed_elements[k]);
			}
		}
	}
	print_line(vformat("Checking for valid conversion ended - all files(%d), files which would be converted(%d), files which would not be converted(%d).", collected_files.size(), converted_files, collected_files.size() - converted_files));
	uint64_t conversion_end_time = Time::get_singleton()->get_ticks_msec();
	print_line(vformat("Conversion of all files took %10.3f seconds.", (conversion_end_time - conversion_start_time) / 1000.0));
	return true;
}
Vector<String> ProjectConverter3To4::check_for_files() {
	Vector<String> collected_files = Vector<String>();
	Vector<String> directories_to_check = Vector<String>();
	directories_to_check.push_back("res://");
	while (!directories_to_check.is_empty()) {
		String path = directories_to_check.get(directories_to_check.size() - 1); 
		directories_to_check.resize(directories_to_check.size() - 1); 
		Ref<DirAccess> dir = DirAccess::open(path);
		if (dir.is_valid()) {
			dir->set_include_hidden(true);
			dir->list_dir_begin();
			String current_dir = dir->get_current_dir();
			String file_name = dir->_get_next();
			while (file_name != "") {
				if (file_name == ".git" || file_name == ".godot") {
					file_name = dir->_get_next();
					continue;
				}