TypeError: unsupported operand type(s) for /: 'NoneType' and 'str'

Hello. When i launch protontricks with flag --gui its show not all games(only 2 of them) and when i select one of them its crashes.
```
pivnoi@pivnoi:~$ flatpak run com.github.Matoking.protontricks -v --gui
protontricks (INFO): Running inside Flatpak sandbox, version 1.6.5.
protontricks (WARNING): Flatpak version is too old (<1.12.1) to support sub-sandboxes. Disabling bwrap. --no-bwrap will be ignored.
protontricks (INFO): Found Steam directory at /home/pivnoi/.var/app/com.valvesoftware.Steam/data/Steam. You can also define Steam directory manually using $STEAM_DIR
protontricks (INFO): Using default Steam Runtime at /home/pivnoi/.steam/root/ubuntu12_32/steam-runtime
protontricks (INFO): WINETRICKS environment variable is not available. Searching from $PATH.
protontricks (INFO): Found 1 Steam library folders
protontricks (INFO): Currently logged-in Steam user: equesvasil
protontricks (INFO): Couldn't find custom shortcuts. Maybe none have been created yet?
protontricks (INFO): Using 'yad' as GUI provider
protontricks (INFO): Found active compatibility tool: Proton 5.13
protontricks (INFO): Active compatibility tool is a Proton installation
protontricks (INFO): WINE environment variable is not available. Setting WINE environment variable to Proton bundled version
Traceback (most recent call last):
File "/app/bin/protontricks", line 8, in
sys.exit(cli())
File "/app/lib/python3.9/site-packages/protontricks/cli/main.py", line 28, in cli
main(args)
File "/app/lib/python3.9/site-packages/protontricks/cli/util.py", line 143, in wrapper
return cli_func(self, *args, **kwargs)
File "/app/lib/python3.9/site-packages/protontricks/cli/main.py", line 220, in main
run_command(
File "/app/lib/python3.9/site-packages/protontricks/util.py", line 352, in run_command
str(proton_app.proton_dist_path / "bin" / "wine")
TypeError: unsupported operand type(s) for /: 'NoneType' and 'str'
```

Tái hiện lỗi crash bằng lệnh đã được báo cáo `flatpak run com.github.Matoking.protontricks -v --gui`. Bắt đầu tại `protontricks/cli/main.py` và lần theo lời gọi vào `protontricks/util.py`, đặc biệt là `run_command` gần traceback. Hoàn tất khi GUI liệt kê các game như mong đợi và việc chọn một game không còn gây ra TypeError đã được báo cáo.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.