In the PWA installed via Edge (only, not other browsers), back button semi-broken when the app is offline (and only when offline)

[Jaifroid]

This is very bizarre. When my computer is offline, the PWA installed via Edge displays an odd issue: when navigating back, the previous page is loaded and displayed briefly, but then blanks out. This doesn't occur when the app is online. In the PWA installed via Chrome, this does not occur offline or online.

Additionally, there is some slowdown when offline compared to online. I suspect an installed extension is playing up and is trying to contact an online site, fails, and the browser is waiting for the failure.

Be that as it may, this potentially exposes a race condition in the app which should be eliminated if it is real and not an artefact of a buggy extension. It should not affect the app in this way. The back history code is very old, and possibly needs to be more carefully integrated with the detection of the window/frame in which content is to be displayed.