show snackbar on update ready

[incognitojam]

Preview

Related:

• Gracefully handle missing code bundles (no internet or app updated) #312

[adeebshihadeh]

Can we just reload instead?

[incognitojam]

I guess if we are OK with losing whatever state the app has at that time, then yeah, although I guess there isn't much state that isn't in the URL right now.

I'm also going to look into this a bit more because apparently it can cause bugs if for example multiple tabs are open and you switch service worker.
https://redfin.engineering/how-to-fix-the-refresh-button-when-using-service-workers-a8e27af6df68

[incognitojam]

In Create React App, the default service worker installs updates immediately when available and discards the old cache, causing the "chunk failed to load" errors when the user tries to load other routes (#312) since they are still browsing on the old site with old JS/HTML referencing now non-existent resources.

We can fix this by adding our own service-worker.js which doesn't immediately call skipWaiting(). If we want to update sooner than waiting for all tabs to be closed, we can prompt the user and/or call skipWaiting() before reloading all open tabs.