[BUG] "Empty error message" when trying to add a new user to a private group

[rafaelks]

Description:

As a normal user, I can see the button to add new users, but when I try to add I only see an empty error message.

Server Setup Information:

• Version of Rocket.Chat Server: 0.64.2-rc.0
• Operating System: Linux

[ggazzo]

closed by #10564