Undefined index: sync_translations in _weight_get_weight()

I've installed the weight module (required by the "impress" feature module) on my multilingual site and now I get the following errors:
Notice: Undefined index: sync_translations in _weight_get_weight() (line 489 of sites\all\modules\weight\weight.module).

The line in the code is the following:

489 if ($settings['sync_translations']) {
490 $nid = $node->tnid;

Any ideas on how to solve this