### 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 (parts.size() == 1) {
				String opposite = parts[0] == "true" ? "false" : "true";
				line = line.substr(0, start) + "set_ignore_rotation(" + opposite + ")";
			}
		}
	}
	//  
	if (line.contains("OS.get_window_safe_area(")) {
		int start = line.find("OS.get_window_safe_area(");
		int end = get_end_parenthesis(line.substr(start)) + 1;
		if (end > -1) {
			Vector<String> parts = parse_arguments(line.substr(start, end));
			if (parts.size() == 0) {
				line = line.substr(0, start) + "DisplayServer.get_display_safe_area()" + line.substr(end + start);
			}
		}
	}
	//  
	if (contains_function_call(line, "draw_rect(")) {
		int start = line.find("draw_rect(");
		int end = get_end_parenthesis(line.substr(start)) + 1;
		if (end > -1) {
			Vector<String> parts = parse_arguments(line.substr(start, end));
			if (parts.size() == 5) {
				line = line.substr(0, start) + "draw_rect(" + parts[0] + ", " + parts[1] + ", " + parts[2] + ", " + parts[3] + ")" + line.substr(end + start) + "# " + parts[4] + ") TODOGODOT4 Antialiasing argument is missing";
			}
		}
	}
	// 
	if (contains_function_call(line, "get_focus_owner()")) {