### 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)

found_renames.append(line_formatter(current_line, "slave func", "@rpc func", line));
				}
			}
			if (line.contains("puppet")) {
				old = line;
				line = reg_container.keyword_gdscript_puppet.sub(line, "@rpc func", true);
				if (old != line) {
					found_renames.append(line_formatter(current_line, "puppet func", "@rpc func", line));
				}
			}
			if (line.contains("puppet")) {
				old = line;
				line = reg_container.keyword_gdscript_puppetsync.sub(line, builtin_escape("@rpc(\"call_local\") func", builtin), true);
				if (old != line) {
					found_renames.append(line_formatter(current_line, "puppetsync func", builtin_escape("@rpc(\"call_local\") func", builtin), line));
				}
			}
			if (line.contains("master")) {
				old = line;
				line = reg_container.keyword_gdscript_master.sub(line, "@rpc func", true);
				if (old != line) {
					found_renames.append(line_formatter(current_line, "master func", "@rpc func", line));
				}
			}
			if (line.contains("master")) {
				old = line;
				line = reg_container.keyword_gdscript_master.sub(line, builtin_escape("@rpc(\"call_local\") func", builtin), true);
				if (old != line) {
					found_renames.append(line_formatter(current_line, "mastersync func", builtin_escape("@rpc(\"call_local\") func", builtin), line));
				}