Fatal error: Cannot use object of type stdClass as array in advagg\advagg.module on line 1909

Who knows why, ['ajaxPageState']['css'] is an object:

  $setting['ajaxPageState']['css'] = (object) array_fill_keys(array_keys($css), 1);

While ['ajaxPageState']['js'] is a keyed array.

The error is from the brand new advagg_cleanup_settings_array:

  // Remove inline css from the ajaxPageState data.
  if (isset($data['ajaxPageState']['js'])) {
    foreach ($data['ajaxPageState']['css'] as $key => $value) {
      if (!advagg_remove_short_keys($key)) {
        unset($data['ajaxPageState']['css'][$key]);
      }
    }
  }

The previous logic does not seem right, it is mixing css and js, and not taking into account that css is an object instead of a keyed array.

Patch coming...