Account in flask, Sql Aalchemy is created but I get werkzeug error AttributeError: 'NoneType' object has no attribute 'is_active'

Question

I am building a flask web app using sql alchemy as database, when I try to make a new account it gives me error AttributeError: 'NoneType' object has no attribute 'is_active' in werkzeug, but the account is created just gives me an error. It says that error is in this part

from flask import Blueprint, render_template, request, flash, redirect, url_for
from .models import User
from werkzeug.security import generate_password_hash, check_password_hash
from . import db
from flask_login import login_user, login_required, logout_user, current_user

@auth.route('/sign-up', methods=['GET', 'POST'])
def sign_up():
    if request.method == 'POST':
        email = request.form.get('email')
        username = request.form.get('username')
        password1 = request.form.get('password1')
        password2 = request.form.get('password2')

        user = User.query.filter_by(email=email).first()

        if user:
            flash('Korisnik već postoji', category='error')
        elif len(email) < 4:
            flash('Nepostojeća E-mail adresa', category='error')
        elif len(username) < 2:
            flash('Korisničko ime je prekratko', category='error')
        elif password1 != password2:
            flash('Lozinke se ne podudaraju', category='error')
        elif len(password1) < 7:
            flash('Lozinka je prekratka', category='error')
        else:
            new_user = User(email=email, username=username, password=generate_password_hash(password1))
            db.session.add(new_user)
            db.session.commit()
            login_user(user, remember=True)
            flash('Uspjeh', category='success')
            return redirect(url_for('views.index'))

    return render_template("sign_up.html", user=current_user)

Specifically in this line:

login_user(user, remember=True)

Thanks to everyone!