fix for multi-turn conv.

app.py

@@ -152,7 +152,7 @@ st.caption(f"Powered by `llama.cpp` | Model: {selected_model['filename']}")
 user_input = st.chat_input("Ask something...")
 
 if user_input:
-    if len(st.session_state.chat_history) % 2 == 1:
+    if st.session_state.chat_history and st.session_state.chat_history[-1]["role"] == "user":
         st.warning("Please wait for the assistant to respond before sending another message.")
     else:
         st.session_state.chat_history.append({"role": "user", "content": user_input})