### 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)

#include "project_converter_3_to_4.h"
#ifndef 
#include "modules/modules_enabled.gen.h" 
#ifdef 
#include "core/error/error_macros.h"
#include "core/io/dir_access.h"
#include "core/io/file_access.h"
#include "core/object/ref_counted.h"
#include "core/os/time.h"
#include "core/templates/hash_map.h"
#include "core/templates/list.h"
#include "editor/renames_map_3_to_4.h"
#include "modules/regex/regex.h"
static String make_regex_gds_os_property_set(String name_set) {
	return String("\\bOS\\.") + name_set + "\\s*\\((.*)\\)";
}
static String make_regex_gds_os_property_assign(String name) {
	return String("\\bOS\\.") + name + "\\s*=\\s*([^#]+)";
}
static String make_regex_gds_os_property_get(String name, String get) {
	return String("\\bOS\\.(") + get + "_)?" + name + "(\\s*\\(\\s*\\))?";
}
class ProjectConverter3To4::RegExContainer {