my $numberset = param('value');
if ($numberset eq "") {
        $numberset = 1;
} elsif ($numberset eq 0) {
        $numberset = 1;
}
[download]

Rather than testing for string emptiness and numerical zero, you could change the above snippet to one simple line. It will catch undefined, empty string, or number zero:

my $numberset = param('value') || 1;
[download]

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