create the folder if it doesn't exist

.gitignore

@@ -141,4 +141,4 @@ frontend/package-lock.json
 bang-workspace.code-workspace
 
 .vscode/
-backend/games.pickle
+backend/save/*

backend/server.py

@@ -813,6 +813,8 @@ def save_games():
     while True:
         sio.sleep(2)
         if not save_lock:
+            if not os.path.exists("save"):
+                os.mkdir("save")
             with open('./save/games.pickle', 'wb') as f:
                 pickle.dump([g for g in games if g.started and not g.is_replay and not g.is_hidden], f)