Tracking event on plugin exit

Hello,

I have installed Mixpanel in Figma to track events, and I would like to track an event when the user exits the plugin. I have written the following code:

figma.on('close', () => {
  figma.ui.postMessage({
    type: 'bg:exit',
  });
});

In the UI, I retrieve the message to send the event to Mixpanel :

  React.useEffect(() => {
    // This is how we read messages sent from the plugin controller
    window.onmessage = async (event) => {
      const {type, message} = event.data.pluginMessage;
      switch (type) {
        case 'bg:exit':
          mixpanel.track('leave-app'); //
          break;
...

However, I believe that once we exit, the UI closes, and the event is never sent. I tried adding a sleep function in the close event, but that didn’t work either. Does anyone have any ideas?

(Note: “Sleep” in this context likely refers to a delay or pause in the code execution.)