### 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)

print_line(vformat("Trying to convert\t%d/%d file - \"%s\" with size - %d KB", i + 1, collected_files.size(), file_name.trim_prefix("res://"), file_size / 1024));
		Vector<String> reason;
		bool is_ignored = false;
		uint64_t start_time = Time::get_singleton()->get_ticks_msec();
		if (file_name.ends_with(".shader")) {
			DirAccess::remove_file_or_error(file_name.trim_prefix("res://"));
			file_name = file_name.replace(".shader", ".gdshader");
		}
		if (file_size < uint64_t(maximum_file_size)) {
			
			if (file_name.ends_with(".gd")) {
				fix_tool_declaration(source_lines, reg_container);
				rename_classes(source_lines, reg_container); 
				rename_common(RenamesMap3To4::enum_renames, reg_container.enum_regexes, source_lines);
				rename_colors(source_lines, reg_container); 
				rename_common(RenamesMap3To4::gdscript_function_renames, reg_container.gdscript_function_regexes, source_lines);
				rename_gdscript_functions(source_lines, reg_container, false); 
				rename_common(RenamesMap3To4::project_settings_renames, reg_container.project_settings_regexes, source_lines);
				rename_gdscript_keywords(source_lines, reg_container, false);
				rename_common(RenamesMap3To4::gdscript_properties_renames, reg_container.gdscript_properties_regexes, source_lines);
				rename_common(RenamesMap3To4::gdscript_signals_renames, reg_container.gdscript_signals_regexes, source_lines);
				rename_common(RenamesMap3To4::shaders_renames, reg_container.shaders_regexes, source_lines);
				rename_common(RenamesMap3To4::builtin_types_renames, reg_container.builtin_types_regexes, source_lines);
				rename_common(RenamesMap3To4::theme_override_renames, reg_container.theme_override_regexes, source_lines);
				custom_rename(source_lines, "\\.shader", ".gdshader");
			} else if (file_name.ends_with(".tscn")) {
				rename_classes(source_lines, reg_container); 
				rename_common(RenamesMap3To4::enum_renames, reg_container.enum_regexes, source_lines);
				rename_colors(source_lines, reg_container); 
				rename_common(RenamesMap3To4::gdscript_function_renames, reg_container.gdscript_function_regexes, source_lines);