That doesn't work. See Re^3: Why am I getting "premature end of script header"? - eval { use } for an explanation. What one could do is replace the aformentioned

BEGIN {
   eval("
      use LWP::UserAgent ();
      use HTTP::Request::Common;
   ");

   if ($@) {
      ...
   }
}

...
[download]

with

BEGIN {
   eval {
      require LWP::UserAgent;
      require HTTP::Request::Common;
      import HTTP::Request::Common;
   };

   if ($@) {
      ...
   }
}

...
[download]

The difference between the two is just a question of style.