When I have insatalled Chat, all is ok.

But when I decided to delete some useres from User list (User management \ Users \ delete)
I have batch of errors :

# Unable to send e-mail. Please contact the site admin, if the problem persists.

# recoverable fatal error: Argument 1 passed to chatroom_clear_cached_user() must be an instance of stdClass, boolean given, called in /hsphere/local/home/***/sites/all/modules/chatroom/chatroom.module on line 20 and defined in /hsphere/local/home/***/sites/all/modules/chatroom/chatroom.module on line 30.

Please let me know if this issue is duplicated or not.
And when it will be fixed?