die "invalid keys in declarative specification file\n" if (%{$declSpec});

        die "invalid keys ($declSpec) in declarative specification file\n" if (%{$declSpec});

    die "command `@{$args{cmd}}' failed with exit status $res->{status}" if $res->{status};

    die "command `@{$args{cmd}}' failed with exit status $res->{status} in $args{dir}" if $res->{status};