fix: check data is not None

backend/data.py

@@ -102,7 +102,8 @@ def load_cot_data():
     del dataset
     config_data = []
     for data in df_cottraces.config_data.to_list():
-        config_data.append(dict(data))
+        if data is not None:
+            config_data.append(dict(data))
     del df_cottraces
     df_cotconfigs = pd.DataFrame(config_data)
     df_cotconfigs.drop_duplicates(inplace=True, ignore_index=True)