auth 미들웨어 관련 질문

const jwt = require("jsonwebtoken");
const User = require("../models/User");

let auth = async (req, res, next) => {
  // 토큰을 request headers에서 가져오기
  const authHeader = req.headers["authorization"];

  // Bearer ooerkogkeorkgoek.erogkoerkog.eorgkoerkgoerkgokg
  const token = authHeader && authHeader.split(" ")[1];
  if (token === null) return res.sendStatus(401);

  try {
    // 토큰이 유효한 토큰인지 확인
    const decode = jwt.verify(token, process.env.JWT_SECRET);
    const user = await User.findOne({ "_id": decode.userId });
    if (!user) {
      return res.status(400).send("없는 유저입니다.");
    }

    req.user = user;
    next();
  } catch (error) {
    next(error);
  }
};

module.exports = auth;

기존에

"_id"로 되어있을 때,

C:\Users\zink8060\Desktop\fullstack-app\back\node_modules\express\lib\router\route.js:211

throw new Error(msg);

^

Error: Route.get() requires a callback function but got a [object Object]

at Route.<computed> [as get] (C:\Users\zink8060\Desktop\fullstack-app\back\node_modules\express\lib\router\route.js:211:15)

at proto.<computed> [as get] (C:\Users\zink8060\Desktop\fullstack-app\back\node_modules\express\lib\router\index.js:521:19)

at Object.<anonymous> (C:\Users\zink8060\Desktop\fullstack-app\back\src\routes\users.js:7:8)

at Module._compile (node:internal/modules/cjs/loader:1246:14)

at Module._extensions..js (node:internal/modules/cjs/loader:1300:10)

at Module.load (node:internal/modules/cjs/loader:1103:32)

at Module._load (node:internal/modules/cjs/loader:942:12)

at Module.require (node:internal/modules/cjs/loader:1127:19) at require (node:internal/modules/helpers:112:18)

at Object.<anonymous> (C:\Users\zink8060\Desktop\fullstack-app\back\src\index.js:33:19)

해당 오류가 있었는데,해당 부분을 _id로 바꿨더니 정상적으로 서버가 동작합니다.

const jwt = require("jsonwebtoken");
const User = require("../models/User");

let auth = async (req, res, next) => {
  // 토큰을 request headers에서 가져오기
  const authHeader = req.headers["authorization"];

  // Bearer ooerkogkeorkgoek.erogkoerkog.eorgkoerkgoerkgokg
  const token = authHeader && authHeader.split(" ")[1];
  if (token === null) return res.sendStatus(401);

  try {
    // 토큰이 유효한 토큰인지 확인
    const decode = jwt.verify(token, process.env.JWT_SECRET);
    const user = await User.findOne({ _id: decode.userId });
    if (!user) {
      return res.status(400).send("없는 유저입니다.");
    }

    req.user = user;
    next();
  } catch (error) {
    next(error);
  }
};

module.exports = auth;

하지만 강사님의 코드에는 "_id"로 되어있는데, 버전문제일까요? 아니면 다른 문제가 있을까요?