Black screen instead of exception page

[Dreamescaper]

In most cases for me when exception happens I simple see fully black screen. I see some text when try to scroll the page, but that doesn't help. That makes debugging hell of a lot harder, considering that exceptions are not logged anywhere else!

I'm trying to find concise repro case for this behavior.

Details


[Eilon]

Oh I wonder if this is related to dark/light mode? That's probably a bug in the default error screen.

Or, it kind of looks like you've entered The Matrix! (But with blue text instead of green.)

[Dreamescaper]

No, not related to dark/light mode. Under some conditions it's ok, sometimes like that with same device settings.

[Eilon]

Hmm that's quite odd then. I think for that screen it might not set all the foreground/background colors and if you're in dark/light mode that can create bad combinations (e.g. black on black). That's usually the problem when I see such problems.

[Eilon]

This is the error UI:

https://github.com/xamarin/MobileBlazorBindings/blob/master/src/Microsoft.MobileBlazorBindings/ErrorPageHelper.cs#L24-L55

Looking at it now, I don't see any colors set at all, so this is certainly odd. But maybe setting explicit colors is best to avoid any risk of inheriting some bad color combinations from something.

[Dreamescaper]

Sometimes I get the opposite - simple white screen, nothing else.

[Eilon]

I'm guessing it's doing black on black and white on white. I think setting explicit colors is the right approach.

[Eilon]

It would be nice to be theme-aware using a little helper like this:

https://github.com/Eilon/Rezipe/blob/master/src/Rezipe/RezipeBaseComponent.cs#L29-L32

[Dreamescaper]

OK, I see that I get simple white screen when my Shell fails to create, and I had no such line in my App: MainPage = new ContentPage();

(didn't think that it mattered).

But adding this line fixed this particular issue - not the black screen though, so I keep digging.

[Eilon]

Ah yes you need to set some initial value for MainPage because all the Blazor stuff loads async. So you could have just an empty ContentPage or you could even put a splash screen there. The Blazor stuff loads very quickly (depending on the app) so there's usually not much to do aside from setting some default value.

[Dreamescaper]

Yeah, I was just surprised that that line would affect error screen. I mean, everything else works fine for me without that line.

[Eilon]

Yeah that's certainly bizarre.

[Dreamescaper]

Ok, so I get this black screen when I attempt to render EditForm component (the one for Web :) ). It obviously wasn't able to render that (fails with KeyNotFoundException), and attempts to show Error page. I don't know why it fails to display it though.

I have seen such behavior under other conditions, but can't recall anything right now.

[Dreamescaper]

However I checked that it does help to BackgroundColor to white explicitly.

[Eilon]

Thank you for sending the PR, it is now merged!