v2.8.2 — Fix all None-stars sort crashes

Three sites in v2_optimizer where -x.get('stars', default) crashed with TypeError: bad operand for unary -: 'NoneType' when the field exists as null in inventory. Fixed with -(x.get('stars') or default) pattern at: sort_rec (line 756), trending_pool (line 1036), sorted_links (line 1456).