That's a problem with the CGI.pm that comes with AS 5.6.1. Try to upgrade it from CPAN.

In AS 5.8.0, it reads:

($param,$value) = split('=',$_,2);
next unless defined $param;  # skip - no error !
next if $NO_UNDEF_PARAMS and not defined $value;
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While in AS 5.6.1 it reads:

($param,$value) = split('=',$_,2);
$value = '' unless defined $value;
$param = unescape($param);  # "uninitialized" error !
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