use Users;
use Error;
my $error = new Error;

($formatted_users = &format(&Users::get_users($filehandle))
  or $error->handle or $Users::error->handle;

====================OR====================
use Users;
use Error;
my $error = new Error;

($formatted_users = &format(&Users::get_users($file_handle,$error)))
        or $error->handle;