regardless of either:

$lwpcurl->{agent}->setopt( CURLOPT_FILE, \$fh );
$lwpcurl->{agent}->setopt( CURLOPT_FILE, $fh );
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both generate the same previous error:

Can't use an undefined value as filehandle reference at /home/geof/httppost/lib/perl5/site_perl/5.8.8/LWP/Curl.pm line 236.