Update app.py

app.py

@@ -436,7 +436,7 @@ if __name__ == '__main__':
             if 'chat_id' not in st.session_state:
                 st.session_state.chat_id = st.selectbox(
                     label='Choose a conversation',
-                    options=['New Chat'] + list(conversations.keys()),
+                    options=[None] + list(conversations.keys()),
                     format_func=lambda x: conversations.get(x, 'New Chat'),
                     placeholder='New Chat',
                 )