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'
```

Reproduisez le crash avec la commande signalée `flatpak run com.github.Matoking.protontricks -v --gui`. Commencez dans `protontricks/cli/main.py` et suivez l’appel jusqu’à `protontricks/util.py`, en particulier `run_command` près de la trace d’exécution. Le travail est terminé lorsque l’interface graphique liste les jeux attendus et que la sélection de l’un d’eux ne provoque plus le TypeError signalé.

Rédigé par le modèle d'indexation à partir du texte de l'issue.