Page does not work offline warning

Hello,

I am getting “Page does not work offline” warning when testing site with Chrome Lighthouse or PWABuilder (https://www.pwabuilder.com/). This also prevents created PWA application from being uploaded to Google Play, as it requires website to work offline.

Can offline functionality be enabled in superPWA, or should we try to create it manually?

Chrome console log at superpwa.com (same errors as with my own site):

The FetchEvent for "https://superpwa.com/?utm_source=superpwa&utm_medium=pwa" resulted in a network error response: the promise was rejected.
Promise.then (async)
(anonymous) @ superpwa-sw.js:74

(index):1 Site cannot be installed: Page does not work offline. Starting in Chrome 93, the installability criteria is changing, and this site will not be installable. See https://goo.gle/improved-pwa-offline-detection for more information.

superpwa-sw.js:1 Uncaught (in promise) TypeError: Failed to fetch

The page I need help with: [log in to see the link]