fix issue in the chat interface.

app.py

@@ -570,12 +570,20 @@ async def stream_agent_response(question: str, chat_history: List) -> List[Dict]
             assistant_message["content"] = f"## ❌ Error\n\n{error_msg}"
         
         # Return the message in the correct format for Gradio Chatbot
-        # Format: [(user_message, assistant_message)]
-        return [(None, assistant_message["content"])]
+        # Format: [(user_message, assistant_message), ...]
+        # Ensure we're returning a list of tuples where each tuple is (user_msg, bot_msg)
+        if isinstance(assistant_message, dict) and "content" in assistant_message:
+            return [(None, assistant_message["content"])]
+        elif isinstance(assistant_message, str):
+            return [(None, assistant_message)]
+        else:
+            # Fallback: convert to string representation
+            return [(None, str(assistant_message))]
         
     except Exception as e:
         error_msg = f"## ❌ Error\n\nOcurrió un error al procesar tu solicitud:\n\n```\n{str(e)}\n```"
         logger.error(f"Error in stream_agent_response: {str(e)}", exc_info=True)
+        # Ensure we return in the correct format: [(user_msg, bot_msg)]
         return [(None, error_msg)]
 
 # Custom CSS for the app