Update app.py

app.py

@@ -198,7 +198,7 @@ if ask:
             logger.info(f"answer: {answer}")
         except Exception as exc:
             logger.error(exc)
-            if "<empty message>" in srt(exc):
+            if "<empty message>" in str(exc):
                 _ = " (invalid api key?)"
             else:
                 _ = ""