## warning - segfaults in 5.6.1
{
  package UndefError;

  use overload (
    q[""]    => sub { undef },
    bool     => sub { undef },
    '0+'     => sub { undef },
    fallback => 1
  );

  sub new { bless [] }
}

eval {
  die UndefError->new;
};
warn "ack - $@" if $@;
warn "object error - $@" if ref $@;

__output__

object error -  at - line 19.