Problems getting response of API request using Postman error { } [duplicate]

I created some documents in MongoDB that are Families, Users, Devices (https://i.stack.imgur.com/oeDU0.png)
What I’m trying to do is to display all devices within a specific family using the Id from http request. For example, http://localhost:8567/get?familyId=65f1dcc828d6b2d79bb2f4b4

Here is the models in VSCODE

My router:

const router = require('express').Router();
const DevicesControl = require('../Controller/DevicesController');

// GET
router.get('/get', DevicesControl.getFamilyDevices);
module.exports = router;

My controller:

const mongoose = require('mongoose');
const Devices = require('../HomeModel/Devices');
const Families = require('../HomeModel/Families');
const ObjectId = mongoose.Types.ObjectId

const DevicesControl = {

    getFamilyDevices: async (req, res) => {
        try {
            console.log('GET request is active');
            const familyId = req.query.familyId;
            if (!familyId) {
                res.status(404).json('Family not found');
            }
            const foundFamily = await Families.findById(familyId);
            const devices = await foundFamily.devices()
            res.status(200).json(devices)
;
        }
        catch (error) 
        {
           res.status(500).json({ error: 'Error getting Devices', details: error });
        }
    }
};
module.exports = DevicesControl;     

The { } error in Postman here

I tried with simply returning the familyId from the request and it worked just fine. However, when it comes to returning documents everything is different.
I’m hoping the correct response should return the devices in ‘Devices’ model (https://i.stack.imgur.com/6EaSw.png)

I looked at some resources, perhaps the error representa empty object. I’m super new to this stuff and can’t solve it myself. Please help me figure out what’s going wrong with that error and how to fix it.