Doesn't work locally

import datetime

from flask_bcrypt import generate_password_hash
from flask_login import UserMixin
from peewee import *

DATABASE = SqliteDatabase('social.db')


class User(UserMixin, Model):
    username = CharField(unique=True)
    email = CharField(unique=True)
    password = CharField(max_length=100)
    joined_at = DateTimeField(default=datetime.datetime.now)
    is_admin = BooleanField(default=False)

    class Meta:
        database = DATABASE
        order_by = ('-joined_at',)

    @classmethod
    def create_user(cls, username, email, password, admin=False):
        try:
            with DATABASE.transaction():
                cls.create(
                    username=username,
                    email=email,
                    password=generate_password_hash(password),
                    is_admin=admin)
        except IntegrityError:
            raise ValueError("User already exists")


def initialize():
    DATABASE.connect()
    DATABASE.create_tables([User], safe=True)
    DATABASE.close()

from flask import (Flask, g, render_template, flash, redirect, url_for)
from flask_login import LoginManager

import models
import forms

DEBUG = True
PORT = 8000
HOST = '0.0.0.0'


app = Flask(__name__)
app.secret_key = 'ncunwcqpcq-e9fhobefvql9wc;03FA;DOFVBAEV'

login_manager = LoginManager()
login_manager.init_app(app)
login_manager.login_view = 'login'


@login_manager.user_loader
def load_user(userid):
    try:
        return models.User.get(models.User.id == userid)
    except models.DoesNotExist:
        return None


@app.before_request
def before_request():
    """Connect to the database before each request."""
    g.db = models.database.db.connect()


@app.after_request
def after_request(response):
    """Close the database connection after each request."""
    g.db.close()
    return response


@app.route('/register', methods=('GET', 'POST'))
def register():
    form = forms.RegistrationForm()
    if form.validate_on_submit():
        flash("You registered!", "success")
        models.User.create_user(
            username=form.username.data,
            email=form.email.data,
            password=form.password.data
        )
        return redirect(url_for('index'))
    return render_template('register.html', form=Form)


@app.route('/')
def index():
    return 'Hey'


if __name__ == '__main__':
    models.initialize()
    try:
        models.User.create_user(
            username="david",
            email="davidb@gmail.com",
            password="12345",
            admin=True
        )
    except ValueError:
        pass
    app.run(debug=DEBUG, host=HOST, port=PORT)