Getting errors on all pages when enabling Bootstrap theme

I am getting this error only when Bootstrap is set as my theme, 4 other themes work just fine. All pages get the HTTP 500 error, including my login page.

PHP Fatal error: Call to a member function sort() on null in /sites/all/modules/search_api/contrib/search_api_views/includes/query.inc on line 138

Here is that section of code.

**
   * Adds a sort to the query.
   *
   * @param string $selector
   *   The field to sort on. All indexed fields of the index are valid values.
   *   In addition, these special fields may be used:
   *   - search_api_relevance: sort by relevance;
   *   - search_api_id: sort by item id;
   *   - search_api_random: random sort (available only if the server supports
   *     the "search_api_random_sort" feature).
   * @param string $order
   *   The order to sort items in - either 'ASC' or 'DESC'. Defaults to 'ASC'.
   */
  public function add_selector_orderby($selector, $order = 'ASC') {
    $this->query->sort($selector, $order);
  }

Why only the Bootstrap theme? I have cleared cache via Drupal and manually deleted the cache tables, so not sure what it could be? A search under this module and on bootstrap theme sites, I could not find anything pointing me somewhere.

Thanks for any input.