updated agent again

agent.py

@@ -177,10 +177,19 @@ def build_graph(provider: str = "groq"):
     # Node
     def assistant(state: MessagesState):
         """Assistant node"""
-        return {"messages": [llm_with_tools.invoke(state["messages"])]}
+        print(f"[Assistant] Received {len(state['messages'])} messages.")
+        try:
+            response = llm_with_tools.invoke(state["messages"])
+            if response is None:
+                return {"messages": []}
+            return {"messages": [response]}
+        except Exception as e:
+            print(f"Error in assistant node: {e}")
+            return {"messages": []}
     
     def retriever(state: MessagesState):
         """Retriever node"""
+        print(f"[Retriever] Input: {state['messages']}")
         similar_question = vector_store.similarity_search(state["messages"][0].content)
         example_msg = HumanMessage(
             content=f"Here I provide a similar question and answer for reference: \n\n{similar_question[0].page_content}",