for my $file (qw(files.txt data.txt)) {
    unlink($file)
        or $!{ENOENT}
        or die("Unable to unlink '$file': $!");
}

##</code><code>##

my $success = 1;
for my $file (qw(files.txt data.txt)) {
    if (!unlink($file) && !$!{ENOENT}) {
        warn("Unable to unlink '$file': $!");
        $success = 0;
    }
}

die("Unable to cleanup") if !$success;