`addPendingMembers` does not work properly yet

[maltee1]

addPendingMembers got me:

{"level":"error","chat_id":"RKRZzOb77EydQmUe350+d7kPd9hjq8kUvXDLgE/OmZU=","room_id":"!KTzSYwyBubPkMjwnhi:maltee.de","action":"handle signal group change","sender_uuid":"redacted1","change_ts":1708865287784,"new_revision":5,"action":"decrypt group change","error":"invalid UUID length","time":"2024-02-25T13:48:06.463002512+01:00","message":"DecryptUUID UserId error"}

Not sure if this is related to the "profile key not found" error of the invitee a bit later in the logs. Maybe we should store profile keys before we do anything else with a given member?

The correspondeng promotePendingMembers for some reason didn't work either. The groupChange itself doesn't complain about anyhting, I'm getting a warning about getting rate limited and shortly after there's a bunch of sendContent too many retries with the invitee as a sender, those seem to be delivery receipts. But other than that it kind of looks like promotePendingMembers is emtpy, because there is no error and ensureJoined should work.

I should probably add better error messages to DecryptGroupChange and handleSignalGroupChange.

Does "invalid UUID length" indicate that decryption went wrong? Or could that be due to some other problem? Wouldn't that mean that the decryption parameters are wrong? Which is odd, because the group master key is taken directly from that group change, so it should be correct.