Usando o consign com express 4x (+ serverless)

Fala pessoal. Tudo bem ?

Eu gostaria de utilizar o consign com o express na versão 4x mais.

Pórem ao tentar utilizar conforme ensinado no curso Aplicações Serverless: Construindo uma API REST retorna o seguinte erro:

Obs: também estou utilizando serverless

offline: ANY /prd/produto (λ: app)
consign v0.1.6 Initialized in /home/ximbinha/myspace/serverLessConsingRoutes
+ ./routes/produto.js
offline: Failure: Cannot read property 'apply' of undefined
TypeError: Cannot read property 'apply' of undefined
    at /home/ximbinha/myspace/serverLessConsingRoutes/node_modules/express/lib/router/index.js:635:15
    at next (/home/ximbinha/myspace/serverLessConsingRoutes/node_modules/express/lib/router/index.js:210:14)
    at Function.handle (/home/ximbinha/myspace/serverLessConsingRoutes/node_modules/express/lib/router/index.js:174:3)
    at Function.router (/home/ximbinha/myspace/serverLessConsingRoutes/node_modules/express/lib/router/index.js:47:12)
    at Consign.into (/home/ximbinha/myspace/serverLessConsingRoutes/node_modules/consign/lib/consign.js:240:17)
    at Object.<anonymous> (/home/ximbinha/myspace/serverLessConsingRoutes/app.js:18:6)
    at Module._compile (internal/modules/cjs/loader.js:1198:30)
    at Module._compile (pkg/prelude/bootstrap.js:1394:32)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1218:10)
    at Module.load (internal/modules/cjs/loader.js:1047:32)
    at Function.Module._load (internal/modules/cjs/loader.js:935:14)
    at Module.require (internal/modules/cjs/loader.js:1087:19)
    at Module.require (pkg/prelude/bootstrap.js:1338:31)
    at require (internal/modules/cjs/helpers.js:73:18)
    at Object.<anonymous> (/home/ximbinha/myspace/serverLessConsingRoutes/handler.js:3:23)
    at Module._compile (internal/modules/cjs/loader.js:1198:30)
    at Module._compile (pkg/prelude/bootstrap.js:1394:32)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1218:10)
    at Module.load (internal/modules/cjs/loader.js:1047:32)
    at Function.Module._load (internal/modules/cjs/loader.js:935:14)
    at Module.require (internal/modules/cjs/loader.js:1087:19)
    at Module.require (pkg/prelude/bootstrap.js:1338:31)
    at require (internal/modules/cjs/helpers.js:73:18)
    at /home/ximbinha/myspace/serverLessConsingRoutes/node_modules/serverless-offline/dist/lambda/handler-runner/in-process-runner/InProcessRunner.js:157:133
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at async InProcessRunner.run (/home/ximbinha/myspace/serverLessConsingRoutes/node_modules/serverless-offline/dist/lambda/handler-runner/in-process-runner/InProcessRunner.js:157:9)

Arquivos:

handler.js

'use strict';

const app           = require('./app');
const serverless    = require('serverless-http')

module.exports.run = serverless(app);

app.js

'use strict';

const express       = require('express');
const bodyParser    = require('body-parser');
const helmet         = require('helmet');
const cors          = require('cors');
const consign       = require('consign');

const app = express();

app.use(cors());
app.use(helmet());
app.use(express.json({ strict: false, type: function () { return true } }));
app.use(express.urlencoded({extended: true}));

consign()
    .include('routes')
    .into(app);

module.exports = app;

produto.js (a parte comentado é como foi passada no curso)

'use strict';

const express = require('express')
const router = express.Router()

    router.get('/produto', (req, res) => {
        res.status(200).send({message: 'listing produto'});
    });

module.exports = router

// module.exports = app => {

//     app.get('/produto', (req, res) => {
//         res.status(200).send({message: 'listing produto'});
//     });

//     app.post('/produto', (req, res) => {
//         res.status(201).send({message: 'creating a produto'});
//     });

//     app.put('/produto/:id', (req, res) => {
//         const id = req.params.id;
//         res.status(200).send({message: `update produto ${id}`});
//     });

//     app.delete('/produto/:id', (req, res) => {
//         const id = req.params.id;
//         res.status(204).send({message: `delete produto ${id}`});
//     });

// };