Update app.py

app.py

@@ -135,8 +135,8 @@ def upload_file(file_obj):
 def demo():
     # with gr.Blocks(theme=gr.themes.Default(primary_hue="sky")) as demo:
     with gr.Blocks(theme=gr.themes.Default(primary_hue="red", secondary_hue="pink", neutral_hue = "sky")) as demo:
-        vector_db = gr.State(None)
-        qa_chain = gr.State(None)
+        vector_db = gr.State()
+        qa_chain = gr.State()
         gr.HTML("<center><h1>RAG PDF chatbot</h1><center>")
         gr.Markdown("""<b>Query your PDF documents!</b> This AI agent is designed to perform retrieval augmented generation (RAG) on PDF documents. The app is hosted on Hugging Face Hub for the sole purpose of demonstration. \
         <b>Please do not upload confidential documents.</b>
@@ -209,8 +209,8 @@ def demo():
             inputs=None, \
             outputs=[chatbot, doc_source1, source1_page, doc_source2, source2_page, doc_source3, source3_page], \
             queue=False)
-    # demo.queue().launch(debug=True)
-    demo.launch(debug=True)
+    demo.queue().launch(debug=True)
+    # demo.launch(debug=True)
 
 
 if __name__ == "__main__":