Mongoose model.methods error: "TypeError: Cannot convert undefined or null to object"

Question

First of all I am really sorry if it is a repeated pos, but I really didn't find a solution for this. Also, I don't have much experience with mongo/express (using mea stack), so my apologies if it is a basic question or I forgot some important information. I am having the following error when trying to compile my app:

C:\Users\backend\node_modules\node-restful\lib\model.js:89 delete self.routes[method]; ^

TypeError: Cannot convert undefined or null to object at C:\Users\backend\node_modules\node-restful\lib\model.js:89:24 at Array.forEach () at Function.Model.methods (C:\Users\backend\node_modules\node-restful\lib\model.js:88:11) at Object. (C:\Users\backend\API\sensor\measure\measureSensorService.js:4:15) at Module._compile (internal/modules/cjs/loader.js:1085:14) at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10) at Module.load (internal/modules/cjs/loader.js:950:32) at Function.Module._load (internal/modules/cjs/loader.js:790:14) at Module.require (internal/modules/cjs/loader.js:974:19) at require (internal/modules/cjs/helpers.js:92:18) at Object. (C:\Users\backend\config\routes.js:6:30) at Module._compile (internal/modules/cjs/loader.js:1085:14) at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10) at Module.load (internal/modules/cjs/loader.js:950:32) at Function.Module._load (internal/modules/cjs/loader.js:790:14) at Module.require (internal/modules/cjs/loader.js:974:19)

And here is my code:

routes.js

const express = require('express')

const workGroupService = require('../API/workGroup/workGroupService')
const workerService = require('../API/worker/workerService')
const locationService = require('../API/location/locationService')
const measureSensorService = require('../API/sensor/measure/measureSensorService')
const locationSensorService = require('../API/sensor/location/locationSensorService')
const heatMeasureContext = require('../API/context/measureContext/heatMeasureContext/heatMeasureContextService')
const ruidMeasureContext = require('../API/context/measureContext/ruidMeasureContext/ruidMeasureContextService')
const workerLocationContext = require('../API/context/workerLocationContext/workerLocationContextService')

module.exports = function(server) {

  //APIs routes
  const router = express.Router()
  server.use('/api', router)

  workGroupService.register(router, '/workGroup')
  workerService.register(router, '/worker')
  locationService.register(router, '/location')
  measureSensorService.register(router, '/measureSensor')
  locationSensorService.register(router, '/locationSensor')
  heatMeasureContext.register(router, '/heatMeasureContext')
  ruidMeasureContext.register(router, '/ruidMeasureContext')
  workerLocationContext.register(router, '/workerLocationContext')
}

measureSensorService.js

const _ = require('lodash')
const MeasureSensor = require('./measureSensor')

MeasureSensor.methods(['get', 'post', 'put', 'delete'])
MeasureSensor.updateOptions({new: true, runValidators: true})

measureSensor.js

const { Schema } = require('mongoose')
const restful = require('node-restful')
const mongoose = restful.mongoose

const Sensor = require('../sensor')

const measureSensor = Sensor.discriminator('MeasureSensor', new mongoose.Schema({
  measurerType: { type: String, required: false, uppercase: true,
    enumValues: ['HEAT', 'RUID'] }
}))

module.exports = restful.model('MeasureSensor')

I read something in the internet about lowering the version of mongoose from 5 to 4, but I tried and didn't work. Here is my package.json dependencies:

"dependencies": {
  "body-parser": "^1.19.0",
  "express": "^4.17.1",
  "express-query-int": "^3.0.0",
  "lodash": "^4.17.21",
  "mongoose": "^5.13.9",
  "mongoose-paginate": "^5.0.3",
  "node-restful": "^0.2.6"
},

I am really lost here, since this issue is happening in the middle of my "routes.js", and my previous routes contain the same service code and seems to work fine.

Please, can you help me?

Thanks in advance!

Update

I've done some more analysis and I understand that this issue is happening due to the use of mongoose discriminators with the node-restful npm module. Still can't solve though. I'm open to alternative options or other ideas to solve the issue. Anyone?