Fix crash caused by unsert user ID in session

kanken_online/__init__.py

@@ -41,7 +41,7 @@ def create_app(test_config=None):
     def update_settings(form):
         db = get_database()
 
-        if session["user_id"]:
+        if "user_id" in session:
             # Set values in the database
             settings = db.execute("SELECT * FROM user_settings WHERE user_id = ?", 
                         (session["user_id"],)