$content = get($url);
$error = 1 unless (defined $content);
[download]

should work from source code examinations, but if it doesn't this roundabout method ought to:

use HTTP::Request;
use LWP::UserAgent;
my $ua = new LWP::UserAgent;
my $request = HTTP::Request->new(GET => $url);
my $response = $ua->request($request);
$error = 1 unless ($response->is_success);
[download]