or: Cannot read properties of undefined (reading 'email') - node.js

Question

I am sending an auth request from chrome to my backend, there is payload chrome developer tool, it seems to have received the object, but I am backend
or: Cannot read properties of undefined (reading 'email')
It gives an error, I printed req.body from the console, it is empty object, what can I do?
backend
postmande works fine and logs in successfully
const { body: { user } } = req
console.log(req.body)
const userLogin = new User();
if (!user.email && !user.password) {
return res.status(402).json({
errors: "Eposta veya şifre zorunlu 😊 ! ",
});
}
return passport.authenticate('local', {
session: false,
successRedirect: '/home',
failureRedirect: '/login'
}, (err, passportUser, info) => {
if (err) {
return next(err)
}
if (passportUser) {
console.log(passportUser)
const user = passportUser
user.token = userLogin.generateJWT(user.email, user.id);
return res.json({ user: passportUser })
}
return res.status(400).json({ message: info });
})(req, res, next)
react fetch (client)
const [email, setEmail] = useState("")
const [password, setPassword] = useState("")
// const token = localStorage.getItem("X-CSRF-TOKEN");
const loginProccsess = async (e) => {
e.preventDefault()
const data = {
"user": {
email,
password
}
}
fetch("/api/auth/login", {
method: "POST",
mode: "cors",
// credentials: "some-origin",
header: {
"Content-type ": "application/json"
},
redirect: "follow",
body: JSON.stringify(data)
}).then((res) => {
console.log(res)
})
.catch(err => console.log(err))
}