Fix typo

app.py

@@ -72,7 +72,7 @@ class BasicAgent:
     def assistant(self, state: State):
         print("Assistant invoked. State:", state)
 
-        response = self.model_with_tools.invoke(messages)
+        response = self.model_with_tools.invoke(state["messages"])
         print("Assistant response:", response)
 
         return {