Code Fix 

foreach my $w (@words) {
  my $lw = length $w;
  if($cols_left > $lw) {
    if($cols_left < $self->columns) {
      $para .= ' ';
      $cols_left--;
    }
    $para .= $w;
    $cols_left -= $lw;
  }
  else {
  # ...