Update app.py

app.py

@@ -145,6 +145,8 @@ if __name__ == '__main__':
                         st.session_state['history'].append(db_chain.intermediate_steps.get("result",''))
 
                     response = "\n\n".join(responses)
+                    if response == "":
+                        response = "Sorry I cannot answer that. Please try again later."
                 else:
                     top_table_names = extract_table_name(llm, question) #[extract_table_name(llm, question)] 
                     print (top_table_names)