a.pl

use v5.10;
use threads;
use Try::Tiny;

my $t = threads->create(sub { 
    my $error = 0;
    try {
      a();
    } catch {
      $error = $_;
    };

    return $error;
  });
my $retval = $t->join;

say "---";

say "retval  = $retval";