Update app.py

app.py

@@ -139,7 +139,7 @@ if st.session_state['generated']:
     with response_container:
         for i in range(len(st.session_state['generated'])):
             message(st.session_state["generated"][i], key=str(i))
-            if len(st.session_state["past"]) > 0:
+            if len(st.session_state["past"]) > 0 and i < len(st.session_state["past"]):
                 message(st.session_state["past"][i], is_user=True, key=str(i) + '_user')