I am trying to add user or overwrite the user document in case the user already exists but I am getting this error:

FirebaseError: Expected first argument to collection() to be a CollectionReference, a DocumentReference or FirebaseFirestore

What am I doing wrong?

import { auth, db }  from "../firebase"
import {doc, setDoc} from 'firebase/firestore'
import { useEffect } from "react";


unction MyApp({ Component, pageProps }) {

  useEffect(() => {
    if(user){
      setDoc(doc(db, 'users', user?.uid), {
        email : user.email,
        lastSeen: firebase.firestore.FieldValue.serverTimestamp(),
        photoURL : user.photoURL
      }, {merge: true});
    }
  }, [user])
}

export default MyApp