OAuth2 Error - Need Help

// require modules
require('dotenv').config();
const express = require('express');
const axios = require('axios');
const url = require('url');
const fs = require('fs');

// load config
const config = require("./config.json");

// website
const port = config.website.port;
const redirect_uri = config.website.redirect_uri;
const webid = config.website.client_id;
const websecret = config.website.client_secret;
const app = express();

app.get('/api/auth/discord/redirect', async (req, res) => {
    const { code } = req.query;

    if (code) {

        // authorize for later use

        try {

            // gain refresh token for later use

            const formData = new url.URLSearchParams({
                client_id: webid,
                client_secret: websecret,
                grant_type: 'authorization_code',
                code: code.toString(),
                redirect_uri: redirect_uri,
            });

            const oauthInfo = await axios.post(`https://discord.com/api/v10/oauth2/token`,
                formData,
            {
                headers: {'Content-Type': 'application/x-www-form-urlencoded',}
            });

            // gain info on user

            const userinfo = await axios.get('https://discord.com/api/v10/users/@me', {
                headers: {
                    'Authorization': `Bearer ${oauthInfo.data.access_token}`
                }
            });
            const userData = {
                "id": userinfo.data.id,
                "username": userinfo.data.username,
                "display_name": userinfo.data.global_name,
                "email": userinfo.data.email,
                "refresh_token": oauthInfo.data.refresh_token
            };

            // edit users.json folder

            let jsonfile = fs.readFileSync("src/users.json").toString()
            let jsonparse = JSON.parse(jsonfile)
            jsonparse[userData.username] = userData
            fs.writeFileSync("src/users.json", JSON.stringify(jsonparse));


        } catch (error) {
            console.log("Error occured:\n", error)
        }
    };

    res.redirect("https://discord.com/oauth2/authorized")


});

// start the bot and website
app.listen(port, () => {console.log(`Running on ${port}.`)});