Tidak bisa nyimpan data user di Firebase saat register

disini saya ingin menyimpan data user saat register, tapi kenapa selalu error mulu

var name     = $('#userName').val();
var email    = $('#userEmail').val();
var password = $('#userPass').val();
var nohp     = $('#userNohp').val();
var alamat   = $('#userAlamat').val();

firebase.auth().createUserWithEmailAndPassword(email, password)
        .then(function(user) {
            var ref = firebase.database().ref().child("user");
            var data = {
                email: email,
                name: name,
                nohp: nohp,
                alamat: alamat,
                id: user.uid
            }
            ref.child(user.uid).set(data).then(function(ref) {
                console.log("Saved");
            }, function(error) {
                console.log(error);
            });
        })
        .catch(function(error) {
            var errorCode = error.code;
            var errorMessage = error.message;
            console.log(errorCode + ' - ' + errorMessage);
        });