Fetching twilio api from node js is not working & throwing error

In this code i have added express endpoints to get twilio endpoints

const config = require("./config");
const express = require("express");
const bodyParser = require("body-parser");
const pino = require("express-pino-logger")();
const { videoToken } = require("./tokens");

const app = express();
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
app.use(pino);

const sendTokenResponse = (token, res) => {
  res.set("Content-Type", "application/json");
  res.send(
    JSON.stringify({
      token: token.toJwt(),
    })
  );
};

app.post("/video/token", (req, res) => {
  const identity = req.body.identity;
  const room = req.body.room;
  const token = videoToken(identity, room, config);
  sendTokenResponse(token, res);
});

In this code i have added function to fetch twilio endpoints but i don't know why it's throwing error of JSON unexpected token at position 0 maybe it's twilio error

const handleSubmit = useCallback(async () => {
    setConnecting(true);
    const data = await fetch("/video/token", {
      method: "POST",
      body: JSON.stringify({
        identity: username,
        room: roomName,
      }),
      headers: {
        Accept: "application/json",
        "Content-Type": "application/json",
      },
    }).then((res) => res.json());
    Video.connect(data.token, {
      name: roomName,
    })
      .then((room) => {
        setConnecting(false);
        setRoom(room);
      })
      .catch((err) => {
        console.error(err);
        setConnecting(false);
      });
  }, [roomName, username]);