Create register: TypeError: Right-hand side of 'instanceof' is not callable Express and Promisify

The following code shows me the error:

TypeError: Right-hand side of 'instanceof' is not callable

There seems to be a problem here with the es6-promisify library

 const {promisify} = require("es6-promisify");

 exports.register = async (req, res, next) => {
    const user = new User({ email: req.body.email, name: req.body.name });
    const register = promisify(User.register, User);
    await register(user, req.body.password);
    res.send("all has been saved")
    next(); // pass to authController.login
  };

The problem might be about es6-promisify library bug. I suggest changing es6-promisify to build-in node module util.

A new working solution should be

const { promisify } = require('util');

exports.register = async (req, res, next) => {
  const user = new User({ email: req.body.email, name: req.body.name });
  const register = promisify(User.register).bind(User);
  await register(user, req.body.password);
  next();
}

Note that just apply await in front of User.register method is not working for sure due to this method is still a normal callback function, you can see on this passport-local-mongoose test case