Undefined index: args in DatabaseLog->findCaller()

I'm using the following code in my custom formatter:

$result = '';
foreach ($variables['#items'] as $delta => $item)
{
    if ($item['access']) {
        $nid = $item['nid'];

        $url = url(drupal_get_path_alias('node/' . $nid), array('absolute' => TRUE));

        $entity_type = 'node';
        $bundle = 'page';
        $nids = array($nid);

        $field_values = db_select('field_revision_field_optional', 'f')
          ->fields('f', array('entity_id', 'field_optional_value'))
          ->condition('entity_type', $entity_type, '=')
          ->condition('bundle', $bundle, '=')
          ->condition('entity_id', $nids, 'IN')
          ->condition('deleted', 0, '=')
          ->execute()
          ->fetchAllKeyed();

        $text = $field_values[$nid];
        $result .= '<a href="' . $url . '">' . $text . '</a>, ';
    }
}

return substr($result, 0, -2);

With having devel's logging mysql-queries enabled I get the following error (its number of duplicates depends on number of values printed by formatter):
Notice: Undefined index: args в функции DatabaseLog->findCaller() (строка 156 в файле /home/u9501/domains/progprofi.ru/includes/database/log.inc).

I don't know whose problem it is: mine, yours or devel module's?