js error

 'use strict';
 
 const shareBuyModel = require('../models/share-buy'),
-    headerModel = require('../../../doraemon/models/header'),
-    co = require('bluebird').coroutine;
+    headerModel = require('../../../doraemon/models/header');
 
 exports.index = (req, res, next) => {
     let activityId = req.query.act_id || 2023,
@@ -77,5 +76,5 @@ exports.getCouponCode = (req, res, next) => {
 
     req.ctx(shareBuyModel).getCouponCode(uid, couponId, protocol).then(result => {
         res.json(result);
-    })
+    }).catch(next);
 };