nodejs custom error response does not take code error argument - node.js

Question

I'm workin with a custom error response that I found in a tutorial. it's working correctly in all the node server, but in a specifies line it doesn't take the argument that specified the error code. It should return a 401 error but instead is returning me a 500 error code.
errorResponse.js
class ErrorResponse extends Error {
constructor(message, statusCode) {
super(message);
this.statusCode = statusCode;
}
}
module.exports = ErrorResponse;
The next is the porcion of code that doesn't working well.
auth.js
return next(new ErrorResponse('Unauthorized', 401))
If I use this aproach the error code is the correct.
return res.status(401).json('Unauthorized')
Edited and share server.js
require('dotenv').config({path: './config.env'});
const express = require('express');
const connectDB = require('./config/db');
const errorHandler = require('./middlewares/error');
connectDB();
const app = express();
app.use(express.json());
app.use('/api/auth', require('./routes/auth'));
app.use('/api/private', require('./routes/private'));
const PORT = process.env.PORT || 5000;
const server = app.listen(PORT, () => console.log('server on port', PORT));
process.on("unhandledRejection", (err, promise) => {
console.log(`logged Error: ${err}`)
server.close(() => process.exit(1))
});
app.use(errorHandler);
error.js
const errorHandler = (err, req, res, next) =>{
let error = { ...err };
error.message = err.message
if(err.code === 11000) {
const message = `Error de duplicación`;
error = new ErrorResponse(message, 400)
}
if(err.name === "ValidationError") {
const message = Object.values(err.errors).map((val) => val.message);
err = new ErrorResponse(message, 400)
}
res.status(error.status || 500 ).json({
succes: false,
error: error.message || "Error del servidor"
})
}