Allow calling "RoomController::formatLastMessage" without a current user.
Allow calling "RoomController::formatLastMessage" without a current user.

This fails with the new type hinting which expects a "IUser" object.

Signed-off-by: Joachim Bauch <f7be0a2a0fb4eba859c8fa4289260059dc564a0d@struktur.de>

nextcloud/spreed,nextcloud/spreed,nextcloud/spreed