Pop up an error message when "Don't allow invites" is enabled and user tries to invite another user

When Don't allow invites on the site, and user tries to invite another user, pop up an error message.
In current situation when Don't allow invites is enabled users are able to select another user to send invite, though the invitation fails, However it would better to pop up message.

Also another suggestion is to disable userpciker field for the users who does not have licenses.