Notice: Undefined index: failed

When running the migration and there are no errors, the following PHP notice is thrown:

Notice: Undefined index: failed in storage_populate_batch_finished() (line 181 of ...\sites\all\modules\contrib\storage_api_populate\storage_api_populate.module).

I fixed this (and the similar processed notice when migrate is run multiple times) with the following changes to lines 180-181:

drupal_set_message(t('@count files processed.', array('@count' => (isset($results['processed']) ? count($results['processed']) : 0))));
    $failed = (isset($results['failed'])) ? count($results['failed']) : 0;