Errors on first load from sendMessage before service worker is installed and activated

[mglaman]

When first visiting, there is an error from the check to see if there is an installed instance:

const checkWww = await sendMessage('analyzePath', ['/persist/drupal'])

Inside the DOMContentLoaded event, we need to ensure the service worker has been activated. We cannot use await serviceWorker.register() since we're in a function and the service worker is a module.

Using await to get the service worker registration doesn't seem to work either.