Can join Matrix portal despite err_needreggednick

[AndrewFerr]

It's possible for a Matrix account to be invited to & stay joined to a portal room for an IRC channel that they should be barred from joining due to their IRC connection not having a registered nick.

To reproduce (rough steps, may be inaccurate):

• Register a nick & join some channels that require one
• Restart the bridge such that your username/password is forgotten & you don't get re-identified automatically
• See that you got kicked from channels with an error of err_needreggednick
• In a DM with the appservice bot, try to re-join one of those channels with !join #<channel_name>

Results:

• The appservice bot responds with "An unknown error happened while handling your command", then "Could not join # on '': err_needreggednick"
• Despite the above, you will have a Matrix invite to the portal room for the channel you tried to join, which you can accept
• Upon accepting the invite, you'll see prior history of the channel, but no new events from IRC will appear

Expected results:

• After an err_needreggednick, your Matrix account should not remain invited to the portal room, nor should you be able to join it

It's possible that this happens only when your Matrix account is on a different homeserver than the bridge & is the only account on your homeserver to have been joined to the portal room.

This isn't so bad of an issue as it's fairly inert, but it is misleading to be joined to a portal room with no connection to IRC events.

[Half-Shot]

Well, if this is all true then it effectively pauses messages in the room when the privacy filter is active..and leaks messages if not. The federated aspect is irrelevant, as the user should be kicked when the fail to join the room.