Invalid index value in function pager_entries_by_key

I ported my 6.x site to 7.x and in pages NOT INCLUDED in pager list array
I got an error in line 286 while evaluating $list[$key] when $key value is "-1"

in order to avoid it I added the following line right before the foreach loop (line 284)

if ($key == -1) {
  $nav['current_index'] = $key;
  return $nav;
}

Thanks for the great module and the port.
Ben