add_message: handle messages where code or text are undef

	}

	for my $message ( @{ $self->{messages} } ) {

		if ( $code eq $message->{code} and $text eq $message->{text} ) {

		if (

			(

				not( not defined $code or not defined $message->{code} )

				or $code eq $message->{code}

			)

			and ( not( not defined $text or not defined $message->{text} )

				or $text eq $message->{text} )

		  )

		{

			$message->{ref_count}++;

			return $message;

		}