Show a better warning when user has unregistered

[nepomuc]

Bug Description

My desktop app is showing a bunch of people from my address book as Signal contacts, while the Android app shows that they aren't. But going into the conversation view with one of these contacts it says below the name and phone number, that this contact IS using Signal. On the other side in the input field below it says that I can only write unencrypted SMS to this contact.

Steps to Reproduce

It's hard to reproduce, because this seems to be random. But I'm suspecting that it could have something to do with contacts that used to be signed up but aren't any more?

Actual Result:

The desktop app shows Signal contacts who are not and this leads to "Send failed" messages when trying to write to them via the desktop app.

Expected Result:

Contacts that don't use Signal should not be listed in the desktop app OR even better (feature request) should be listed but marked as normal SMS contacts, like it's handled in the android app.

Screenshots

Platform Info

Signal Version:

v1.39.6

Operating System:

Windows 10 - 64bit

Linked Device Version:

Android: 5.2.3

Link to Debug Log

https://debuglogs.org/395392492ef08a8b02a3fd2eb513c323826f85e8d783bffeb383b61a6f91b530

[scottnonnenberg-signal]

Yes, if a contact unregisters, we won't remove them from Signal Desktop; you'll still see your messages with them. But new messages won't go through. I'm going to close this.

[nepomuc]

But I have never written any messages to these contacts or received any messages from them via Signal yet. You can see that in the first screenshot. Please reopen this issue again.
Also there's a big chance to solve two problems at once here. By fixing this you could also improve the UX significantly in cases when people unregister. The user wouldn't get a unfriendly error but could be informed that the other user is not using Signal any more. Extra points for disabling the input field as well in these cases.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.