Service Worker gotchas – https://medium.com/kollegorna/service-worker-gotchas-af20a9dab986

service-worker-multilingual-pages.js

const criticalResources = [
        '/sv/',
        '/en/',
        '/sv/offline/',
        '/en/offline/',
      ],
      otherResources = [
        '/sv/projekt/',
        '/sv/om/',
        '/sv/kollegor/',
        '/sv/blogg/',
        '/en/work/',
        '/en/about/',
        '/en/colleagues/',
        '/en/blog/',
      ];