Check if serviceWorker is supported

[tutacat]

Tested working on gecko/firefox and blink/chromium

[tutacat]

Oops, newline

[Offroaders123]

Thanks for the contribution!

I think I didn't add the check for it initially because it seems like all modern browsers support Service Workers nowadays. Is there another situation where navigator.serviceWorker might not be declared?

Information about it does seem to show that the check is used commonplace, however much of the original documentation for Service Workers seems to be from 2016-2018.

I could see a take of wanting to use Dovetail on older browsers that don't support Service Workers, but I'm also not sure how much marketshare those realistic have anymore. Dovetail's backing relies on fairly modern APIs that are in modern browsers too, so much of the actual app wouldn't work even if the Service Worker call didn't break the whole site.

Thanks again for contributing this, I don't mean to be over analyzing this, I just want to see if there's any more info I might not know about whether the check is still viable nowadays. Always something to learn from 😁