Backtraces, once more

bt.pl

my Mu $comp := pir::compreg__Ps('perl6');
$comp.HOW.add_method($comp, 'handle-exception',
    method (|$) {
        my Mu $ex := nqp::atpos(
            pir::perl6_current_args_rpa__P(),
            1
        );
        say 'custom handler';
        say EXCEPTION($ex);
        say BackTrace.new(EXCEPTION($ex));
    }
);

die 'foo';

output

custom handler
foo
  in sub die at src/gen/CORE.setting:370
  in mu <anon> at bt.pl:14