Use whilst instead of forever

this gets rid of the Error object

src/storage/noop.js

@@ -17,6 +17,7 @@ exports = module.exports = {
 };
 
 var assert = require('assert'),
+    BoxError = require('../boxerror.js'),
     debug = require('debug')('box:storage/noop'),
     EventEmitter = require('events');
 
@@ -38,7 +39,7 @@ function download(apiConfig, backupFilePath, callback) {
 
     debug('download: %s', backupFilePath);
 
-    callback(new Error('Cannot download from noop backend'));
+    callback(new BoxError(BoxError.NOT_IMPLEMENTED, 'Cannot download from noop backend'));
 }
 
 function listDir(apiConfig, dir, batchSize, iteratorCallback, callback) {
@@ -60,7 +61,7 @@ function downloadDir(apiConfig, backupFilePath, destDir) {
     process.nextTick(function () {
         debug('downloadDir: %s -> %s', backupFilePath, destDir);
 
-        events.emit('done', new Error('Cannot download from noop backend'));
+        events.emit('done', new BoxError(BoxError.NOT_IMPLEMENTED, 'Cannot download from noop backend'));
     });
     return events;
 }
@@ -109,5 +110,6 @@ function removePrivateFields(apiConfig) {
     return apiConfig;
 }
 
+// eslint-disable-next-line no-unused-vars
 function injectPrivateFields(newConfig, currentConfig) {
 }