Looking at the code in your followup, I'd expect this is down to the use of local $@ just before the eval in _rmap() - if the eval fails, you die $@, which puts the error message in $@, which is then overwritten when the original $@ is restored on unwinding.

I'd suggest it should instead do something like (untested):

  my $error;
  my @got;
  {
    local $@;
    @got = eval { $self->call(); };
    if ($@) {
      if (ref($@) && $@ == $cut) {
         push @return, @$cut;
         next;
       } else {
         $error = $@;
       }
     }
  }
  die $error if $error;
  push @return, @got;
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