Update app.py

app.py

@@ -65,7 +65,7 @@ def handle_file_upload(file, llm_name):
     )
     
     bm25_retriever = BM25Retriever(nodes=documents, similarity_top_k=2, tokenizer=text_splitter.split_text)
-    vector_retriever = VectorIndexRetriever(index=vector_index, similarity_top_k=2)
+    vector_retriever = VectorIndexRetriever(index=index, similarity_top_k=2)
     hybrid_retriever = HybridRetriever(bm25_retriever=bm25_retriever, vector_retriever=vector_retriever)
     chat_engine = ChatEngine(hybrid_retriever)
     response = chat_engine.ask_question(question, llm)