Warning: Invalid argument supplied for foreach() in SearchApiSpellcheckSolr->__construct()

Notice: Undefined property: stdClass::$suggestion in SearchApiSpellcheckSolr->__construct() (line 26 of /private/var/www/insight-platform/sites/all/modules/contrib/search_api_solr/includes/spellcheck.inc).
Warning: Invalid argument supplied for foreach() in SearchApiSpellcheckSolr->__construct() (line 26 of /private/var/www/insight-platform/sites/all/modules/contrib/search_api_solr/includes/spellcheck.inc).

Hi, I'm getting warning message above when I use hook__search_api_solr_search_results_alter() to re-excute the query with suggestion.
below is the code. (solr 4.x)

function mymodule_search_api_solr_search_results_alter(array &$results, SearchApiQueryInterface $query, $response) {  
  //if there's suggestion ...
  if (isset($response->spellcheck->suggestions->collation->collationQuery)) {
    //create a new query with the suggestion
    $collationQuery = str_replace("\"", "", $response->spellcheck->suggestions->collation->collationQuery);
    $collationQueryKeys = explode(" AND ", $collationQuery);
    $collationQueryKeys['#conjunction'] = 'AND';

    //regenerate result with new suggestion query
    $query->keys($collationQueryKeys);
    $collateResults = $query->execute();
    $results['results'] = $collateResults['results'];
    $results['result count'] = $collateResults['result count'];
  }
}

I also attached patch for this.