Give some useful errors when trying to open Mail app when email not set-up yet/ incoming email not turned on

[jdaviescoates]

This is very similar to this thread about Roundcube:
https://forum.cloudron.io/post/129623

I wanted to try out the new Mail app. My main production Cloudron isn't on v10 yet, but I've updated a smaller one to have a play.

But I hadn't even set-up email on that smaller Cloudron.

So when I installed the Mail app and opened it, it seems just like the app was totally broken. There was no clue that it wasn't working/ loading properly because I hadn't set-up email and turned incoming email on yet!

It just gets stuck like this showing "loading" but never loads, and with not side menu items:

Eventually I realised and it was all fine. But I think perhaps Mail (and the other webmail clients) needs some check that at least one domain on the Cloudron has incoming email set-up or something like that. And/ or errors which give clues as to what is actually wrong.

[nebulon]

Good point, we will show a better placeholder UI when the user does not have access to any mailbox.

[nebulon]

This is fixed now, pending an app release.