use Net::LDAP::Util qw(ldap_error_text
                       ldap_error_name) ;

my $msg ; # you will need it several times
$msg = $ldap->bind(%your_bind_params) ;
if ($msg->is_error) {
  my $code = $msg->code ;
  die join "\n",ldap_error_name($code),
                ldap_error_text($code) ;
}