Touch bar widget is not populated via apple script

Hi there,

I am just trying to set up a simple test touch bar button/widget, that should modify the text, adding my widget UUID (based on the documentation) :

(async ()=> {

let widgetConfig = {
    text: "hi there!"   

callBTT('update_touch_bar_widget', {uuid: '6A6D273F-929E-483A-B0CE-419FEFEB1491', json: widgetConfig});



But when I try to run the script, there is no sign of the widget on the touch bar at all. The only way to make the widget appear is to give it a title. What am I missing?