خطأ في JSON عند تسجيل مستخدم جديد في Mern Stack

لقد قمت بإنشاء مشروع باستخدام Mern Stack، و في البداية قمت بإنشاء ملف Index.js وملف auth.js في مجلد الباك إند (مجلد الفرونت إند ليس موجودا حتى الان)، وقمت بإنشاء دالة لعملية تسجيل مستخدم جديد، ولكن عندما أحاول تسجيل مستخدم جديد باستخدام بوستمان، يظهر هذا الخطأ ولا تتم عملية التسجيل 

SyntaxError: Unexpected token } in JSON at position 121
    at JSON.parse (<anonymous>)
    at parse (C:\Users\ه\Desktop\social_media\server\node_modules\express\node_modules\body-parser\lib\types\json.js:89:19)
    at C:\Users\ه\Desktop\social_media\server\node_modules\express\node_modules\body-parser\lib\read.js:128:18
    at AsyncResource.runInAsyncScope (node:async_hooks:203:9)
    at invokeCallback (C:\Users\ه\Desktop\social_media\server\node_modules\express\node_modules\raw-body\index.js:231:16)
    at done (C:\Users\ه\Desktop\social_media\server\node_modules\express\node_modules\raw-body\index.js:220:7)
    at IncomingMessage.onEnd (C:\Users\ه\Desktop\social_media\server\node_modules\express\node_modules\raw-body\index.js:280:7)
    at IncomingMessage.emit (node:events:513:28)
    at endReadableNT (node:internal/streams/readable:1359:12)
    at process.processTicksAndRejections (node:internal/process/task_queues:82:21)

index.js code :

import express from "express";
import bodyParser from "body-parser";
import mongoose from "mongoose";
import cors from "cors";
import dotenv from "dotenv";
import multer from "multer";
import helmet from "helmet";
import morgan from "morgan";
import path from "path";
import { fileURLToPath } from "url";
import { register } from "./controllers/auth.js";

// ** CONFIGURATION ** //
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
dotenv.config();
const app = express();
app.use(express.json());
app.use(helmet());
app.use(helmet.crossOriginResourcePolicy({ policy: "cross-origin" }))
app.use(morgan("common"));
app.use(bodyParser.json({ limit: "30mb", extended: true }));
app.use(bodyParser.urlencoded({ limit: "30mb", extended: true }));
app.use(cors());
app.use("/assets", express.static(path.join(__dirname, 'public/assets')));

/* FILE STORAGE */
const storage = multer.diskStorage({
    destination: function (req, file, cb) {
        cb(null, "public/assets");
    },
    filename: function (req, file, cb) {
        cb(null, file.originalname);
    }
});
const upload = multer({ storage });

/* ROUTES WITH FILES */
app.post("/auth/register", upload.single("picture"), register);

/* MONGOOSE SETUP */
const PORT = process.env.PORT || 6001;
mongoose.connect(process.env.MONGO_URL, {
    useNewUrlParser: true,
    useUnifiedTopology: true,
})
.then(() => {
    app.listen(PORT, () => console.log(`Server Port ${PORT}...`));
})
.catch((error) => console.log(`did not connect cause this error: ${error}`));

auth.js code :

import bcrypt from "bcrypt";
import Jwt from "jsonwebtoken";
import User from "../models/User.js";

/* REGISTER USER */
export const register = async (req, res) => {
    try {
        const {
            name,
            username,
            email,
            password,
            picturePath,
            friends,
            location,
            occupation
        } = req.body;

        const salt = await bcrypt.genSalt();
        const passwordHash = await bcrypt.hash(password, salt);

        const newUser = new User({
            name,
            username,
            email,
            password: passwordHash,
            picturePath,
            friends,
            location,
            occupation,
            viewedProfile: Math.floor(Math.random() * 10_000),
            impressions: Math.floor(Math.random() * 10_000),
        });
        const savedUser = await newUser.save();
        res.status(201).json(savedUser);
    } catch (err) {
        res.status(500).json({ error: err.message });
    }
}

وهذا تعليق أحد المبرمجين على مشكلتي في موقع stackoverflow :

"Unexpected token } in JSON at position 121" — So look at the JSON! (And use a linter on it to make it easier to identify the error)

واستخدمت ESLint ولم يساعدني لمعرفة أين المشكلة