It's actually rather simple.

sub IO::Handle::DESTROY {
  my $deadbody = shift;
  not defined fileno $deadbody
    or close $deadbody
    or die "Cannot close $deadbody: $!";
}
[download]

Of course, this is a global change, but that's life. You can make it regional by putting it inside a local setting:

{
  local *IO::Handle::DESTROY = sub { ... };
  {
    open my $fh, "...";
    ...
  } # will trigger here
}
[download]

The nested parens here ensure that the handle is destroyed before the local sub assignment goes out of scope.