Update app.py

app.py

@@ -73,7 +73,8 @@ async def upload_file(file: UploadFile = File(...)):
 
     # Create or update vector index
     embed_model = HuggingFaceEmbedding(model_name="WhereIsAI/UAE-Large-V1")
-    if vector_index is None:
+    # if vector_index is None:
+    if not hasattr(app.state, "vector_index") or app.state.vector_index is None:
         app.state.vector_index = VectorStoreIndex(nodes, embed_model=embed_model)
         message = "New vector index created and file stored."
     else: