update __call__

app.py

@@ -57,7 +57,11 @@ class BasicAgent:
     def __call__(self, question: str) -> str:
         state = {"messages": [question]}
         out = self.graph.invoke(state)
-        return out["messages"][-1]
+        last_msg = out["messages"][-1]
+        if hasattr(last_msg, "content"):
+            return last_msg.content
+        else:
+            return str(last_msg)
 
 def run_and_submit_all( profile: gr.OAuthProfile | None):
     """