lbry-desktop/static/pwa/serviceWorker.js

// register service worker
if ('serviceWorker' in navigator) {
  navigator.serviceWorker.register('./serviceWorker.js').then(function(reg) {
    // reg.scope must be '/' to allow '/' as start url
  }).catch(function(err) {
    // console.warn('Error whilst registering service worker', err);
  });
}

// used to fetch the manifest file
self.addEventListener('fetch', () => {});