ما سبب خطأ MissingSchemaError: Schema hasn't been registered

عند تشغيل الخادم أحصل على الخطأ التالي:

MissingSchemaError: Schema hasn't been registered for model "Assessment". Use mongoose.model(name, schema)

وذلك هو ملف critique.js:

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

const CritiqueSchema = new Schema({
owner: { type: Schema.Types.ObjectId, ref: 'Person' },
title: String,
commentary: String,
evaluation: { type: Number, default: 0 },
created: { type: Date, default: Date.now }
});

module.exports = mongoose.model('Assessment', CritiqueSchema);

merchandise.js

const mongoose = require("mongoose");
const deepPopulate = require("mongoose-deep-populate")(mongoose);
const Schema = mongoose.Schema;
const mongooseAlgolia = require("mongoose-algolia");

const MerchandiseSchema = new Schema({
classification: { type: Schema.Types.ObjectId, ref: "Grouping" },
owner: { type: Schema.Types.ObjectId, ref: "Person" },
assessments: [{ type: Schema.Types.ObjectId, ref: "Assessment" }],
image: String,
title: String,
description: String,
price: Number,
created: { type: Date, default: Date.now }
});

module.exports = mongoose.model("Merchandise", MerchandiseSchema);

config.js

module.exports = {
database: 'mongodb://localhost:27017/dabdatabase',
port: process.env.PORT || 3000,
secret: 'ganesh123'
};

لا أعلم ما المشكلة مع أن الكود صحيح؟