Finally fixed bug:'NoneType' object is not subscriptable

bot/bot.py

@@ -43,6 +43,10 @@ async def register_user_if_not_exists(update: Update, context: CallbackContext,
             first_name=user.first_name,
             last_name= user.last_name
         )
+        db.start_new_dialog(user.id)
+
+    if db.get_user_attribute(user.id, "current_dialog_id") is None:
+        db.start_new_dialog(user.id)
 
 
 async def start_handle(update: Update, context: CallbackContext):

bot/database.py

@@ -51,8 +51,6 @@ class Database:
 
         if not self.check_if_user_exists(user_id):
             self.user_collection.insert_one(user_dict)
-            
-        # TODO: maybe start a new dialog here?
 
     def start_new_dialog(self, user_id: int):
         self.check_if_user_exists(user_id, raise_exception=True)