Update app_web.py

app_web.py

@@ -211,7 +211,7 @@ def render_chat():
             combined_cat = prompt
             original_query_cat = prompt
             st.session_state.resolution_rounds = 0
-            unresolved_question = None
+            unresolved_question = []
 
         prior_messages = st.session_state.messages[:-1]
         history = [