Javascript 抛出消息；TypeError:第一个参数必须是字符串或缓冲区

我正在尝试以下代码：

app.get('/caminhosRelevantes',function(req,res){

console.log(req.protocol+":/"+req.get('host'));
   var collection = "caminhos";
   var ObjectId = require('mongodb').ObjectID;
   collectionDriver.getCollection(collection, function(error, the_collection) {
        if (error) { 
res.end("<h1>Eerro</h1>");
        }
        else  
          the_collection.aggregate([
  { $match: { id_usuario: "54bef57a14b88ad70a8ab74e" } },
  { $group: { _id: { rua: "$rua", data: "$data" } } },
  { $group: { _id: "$_id.rua", data: { $push: "$_id.data" }, count: { $sum: 1 } } },
  { $match: { count: { $gt: 5 } } }
], function(error,doc) { //C
              if (error) res.end(error);
              else res.end(doc);
            });
   });
});

---

我尝试了

res.status（200）.发送（doc）

而不是

res.end（doc）而且效果很好
 可能是您遇到了如下问题：[link]（）
/server/node_modules/mongodb/lib/mongodb/connection/base.js:242
        throw message;      
              ^
TypeError: first argument must be a string or Buffer
    at ServerResponse.OutgoingMessage.write (http.js:851:11)
    at ServerResponse.OutgoingMessage.end (http.js:985:16)