Fatal error: Cannot use object of type stdClass as array in search_api_sorts/search_api_sorts.module on line 151

When trying to access a View page with a search sort block on it, after updating to 7.x-1.x-dev I got:

Fatal error: Cannot use object of type stdClass as array in ..../search_api_sorts/search_api_sorts.module on line 151

<?php
function search_api_sorts_search_sorts($index_id, $enabled = 1, $reset = FALSE) {
.....
    $index = search_api_index_load($index_id);
    while ($row = $query->fetch()) {
      // Check that this field exists in index.
      if (!empty($index->options['fields'][$row['field']])) {
?>

I am working on a Commerce Kickstart site trying to upgrade to the current version from rc2. It's pretty difficult as something in the search index setup doesn't want to show the sort block. I tried changing the module back to the older version and I still got this fatal error. Is this related to the recent updates on search_api and search_api_db ?

Wish it were easier to diagnose this monster - I tried updating the search_api modules to their new versions just released via drunken_monkey and same result. Also tried changing it to $index = search_api_index_load($index_id, true); to reset the cache on that call.