考虑封面图为空的情况

@@ -282,6 +282,7 @@ renderGoodList();
 
 function changeImgQuality(flag){
     $.each(goodsList,function (index,item){
+        if(!item.goodsImagesList){return true;}
         $.each(item.goodsImagesList, function (_index, _item) {
            if(flag && _item.imageUrl.indexOf('?') == -1){
                 _item.imageUrl = _item.imageUrl + '?imageView2/0/q/75';