### 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)

} else if (file_name.ends_with(".tscn")) {
				changed_elements.append_array(check_for_rename_classes(lines, reg_container));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::enum_renames, reg_container.enum_regexes, lines));
				changed_elements.append_array(check_for_rename_colors(lines, reg_container));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::gdscript_function_renames, reg_container.gdscript_function_regexes, lines));
				changed_elements.append_array(check_for_rename_gdscript_functions(lines, reg_container, true));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::project_settings_renames, reg_container.project_settings_regexes, lines));
				changed_elements.append_array(check_for_rename_gdscript_keywords(lines, reg_container, true));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::gdscript_properties_renames, reg_container.gdscript_properties_regexes, lines));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::gdscript_signals_renames, reg_container.gdscript_signals_regexes, lines));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::shaders_renames, reg_container.shaders_regexes, lines));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::builtin_types_renames, reg_container.builtin_types_regexes, lines));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::theme_override_renames, reg_container.theme_override_regexes, lines));
				changed_elements.append_array(check_for_custom_rename(lines, "\\.shader", ".gdshader"));
			} else if (file_name.ends_with(".cs")) {
				changed_elements.append_array(check_for_rename_classes(lines, reg_container));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::csharp_function_renames, reg_container.csharp_function_regexes, lines));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::builtin_types_renames, reg_container.builtin_types_regexes, lines));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::csharp_properties_renames, reg_container.csharp_properties_regexes, lines));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::csharp_signals_renames, reg_container.csharp_signal_regexes, lines));
				changed_elements.append_array(check_for_rename_csharp_functions(lines, reg_container));
				changed_elements.append_array(check_for_rename_csharp_attributes(lines, reg_container));
				changed_elements.append_array(check_for_custom_rename(lines, "public class ", "public partial class "));
			} else if (file_name.ends_with(".gdshader") || file_name.ends_with(".shader")) {
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::shaders_renames, reg_container.shaders_regexes, lines));
			} else if (file_name.ends_with("tres")) {
				changed_elements.append_array(check_for_rename_classes(lines, reg_container));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::shaders_renames, reg_container.shaders_regexes, lines));
				changed_elements.append_array(check_for_rename_common(RenamesMap3To4::builtin_types_renames, reg_container.builtin_types_regexes, lines));
				changed_elements.append_array(check_for_custom_rename(lines, "\\.shader", ".gdshader"));