callback is not defined, use next when there is an error in controller

services/web/app/coffee/controllers/UserController.coffee

@@ -171,7 +171,7 @@ module.exports =
 		metrics.inc "user.password-change"
 		oldPass = req.body.currentPassword
 		AuthenticationManager.authenticate _id: req.session.user._id, oldPass, (err, user)->
-			return callback(err) if err?
+			return next(err) if err?
 			if(user)
 				logger.log user: req.session.user, "changing password"
 				newPassword1 = req.body.newPassword1
@@ -197,23 +197,23 @@ module.exports =
 					  type:'error'
 					  text:'Your old password is wrong'
 
-	redirectUserToDropboxAuth: (req, res)->
+	redirectUserToDropboxAuth: (req, res, next)->
 		user_id = req.session.user._id
 		dropboxHandler.getDropboxRegisterUrl user_id, (err, url)->
-			return callback(err) if err?
+			return next(err) if err?
 			logger.log url:url, "redirecting user for dropbox auth"
 			res.redirect url
 
-	completeDropboxRegistration: (req, res)->
+	completeDropboxRegistration: (req, res, next)->
 		user_id = req.session.user._id
 		dropboxHandler.completeRegistration user_id, (err, success)->
-			return callback(err) if err?
+			return next(err) if err?
 			res.redirect('/user/settings#dropboxSettings')
 
-	unlinkDropbox: (req, res)->
+	unlinkDropbox: (req, res, next)->
 		user_id = req.session.user._id
 		dropboxHandler.unlinkAccount user_id, (err, success)->
-			return callback(err) if err?
+			return next(err) if err?
 			res.redirect('/user/settings#dropboxSettings')
 
 	deleteUser: (req, res)->