To avoid errors when calling an empty list - aka no related nodes found

I had to tweak the code a little in the module file

    $node_obj = node_load($nid);
    if ($vocid == 'all') {
      $terms = array_keys(similarterms_taxonomy_node_get_terms($node_obj));
    }
    else {
			if($vocid == "1")
			{
				$terms = null;
			}
			else
			{
				$terms = array_keys(similarterms_taxonomy_node_get_terms_by_vocabulary($node_obj, $vocid));
			}
	}