In NodeJS, using simple-odata-server, when insert data in one entity, it inserts data in another entity

I want to use odata in my nodejs project. So i decided to use the package simple-odata-server (https://www.npmjs.com/package/simple-odata-server), that i installed by tapping :

npm i simple-odata-server

My code is inspired by this example (which doesn't work by the way) :

https://codesandbox.io/s/2rzn5?file=/src/index.js:1216-1227

var ODataServer = require("simple-odata-server");
var Adapter = require("simple-odata-server-nedb");
var Datastore = require("nedb");
var http = require("http");

var db = new Datastore({ inMemoryOnly: true });

var model = {
  namespace: "jsreport",
  entityTypes: {
    UserType: {
      _id: { type: "Edm.String", key: true },
      name: { type: "Edm.String" },
      addresses: { type: "Collection(jsreport.AddressType)" }
    },
    ProductType: {
      _id: { type: "Edm.String", key: true },
      name: { type: "Edm.String" },
      description: { type: "Edm.String" },
    }
  },
  complexTypes: {
    AddressType: {
      street: { type: "Edm.String" }
    }
  },
  entitySets: {
    users: {
      entityType: "jsreport.UserType"
    },
    products: {
      entityType: "jsreport.ProductType"
    }
  }
};

var odataServer = ODataServer("https://localhost:1337/");

odataServer.model(model).adapter(
  Adapter(function (coll, cb) {
    cb(null, db);
  })
);

odataServer.cors("*");

http.createServer(odataServer.handle.bind(odataServer)).listen(1337);
console.log("server running on http://localhost:1337");

Then I add data with postman :

POST http://localhost:1337/products with body :

[{ "_id" : "1", "name" :  "banana"}, {"_id" : "2", "name" :  "pineapple"}, {"_id" : "3", "name" :  "coconut"},{"_id" : "4", "name" :  "orange"}]

If I do : GET http://localhost:1337/products I got correct result :

{
    "@odata.context": "https://localhost:1337//$metadata#products",
    "value": [
        {
            "_id": "1",
            "name": "banana"
        },
        {
            "_id": "2",
            "name": "pineapple"
        },
        {
            "_id": "3",
            "name": "coconut"
        },
        {
            "_id": "4",
            "name": "orange"
        }
    ]
}

But if i do GET http://localhost:1337/users I got a weird result :

{
    "@odata.context": "https://localhost:1337//$metadata#users",
    "value": [
        {
            "_id": "1",
            "name": "banana"
        },
        {
            "_id": "2",
            "name": "pineapple"
        },
        {
            "_id": "3",
            "name": "coconut"
        },
        {
            "_id": "4",
            "name": "orange"
        }
    ]
}

Updating the entity products, also update entity users. It means updating an entity update another entity.

I don't know how to solve this.