Not sure about jumble specifically, but we've hit a very similar-sounding class of bug in our own PWA (NOSTRAS) — a stale service worker stuck after a deploy update was the cause both times for us, bad enough that a normal reload didn't fix it either. Worth checking DevTools > Application > Service Workers for one stuck in a weird state, or just clearing site data for the domain once. If that's not it, a console error right before the crash would at least tell you it's a different shape of bug.