my ($self, $item, $idx, $data, %params) = @_;
my $part = SL::DB::Part->load_cached($item->parts_id);
- return unless $item->part;
+ return unless $part;
my $part_unit = $data->{units_by_name}->{ $part->unit };
my $item_unit = $data->{units_by_name}->{ $item->unit };