createProcessImageFiles.js

var createProcessImageFiles = function(folderName, files, createProcessImageFilesCallback) {

    var flow = {

        // Persist each new image file
        createImageDirectory: async.apply(createImageDirectory, folderName),

        // Update images data from the model
        persistImageFiles: ['createImageDirectory', function(callback) {

            async.forEachOf(files, function (file, key, innerCallback) {
                persistImageFile(folderName, file, callback);
            }, function (err) {
                if (err) return callback(err);
                callback(undefined);
            })
        }]
    };

    async.auto(flow, function (error, results) {
        if (error) {
            return createProcessImageFilesCallback(error);
        }
        createProcessImageFilesCallback(undefined, results);
    });
};

no veo q uses el innerCallback