OverwriteModelError после компиляции Mongoose

Question

Я сталкиваюсь с этой ошибкой всякий раз, когда пытаюсь сохранить пользователя, когда он подписывается на ключ API в этом API, который я создаю.

Я пытался использовать решения из других вопросов, похожих на мои, но для жизни я не могу найти решение. Любая помощь приветствуется.

Схема пользователя

const mongoose = require('mongoose');

const Schema = mongoose.Schema;

const UserSchema = new Schema({
  _id: Schema.Types.ObjectId,
  email: String,
  apikey: String,
});

module.exports.UserSchema = mongoose.model('User', UserSchema, 'User');

Сохранить нового пользователя

const uuidv4 = require('uuid/v4')
const User = require('../schemas/User')

function saveNewUser(email){
  let uuid = uuidv4()
  let newUser = new User({email: email, apiKey: uuid})

  newUser.save((err) => {
    if(err) console.log(err)

  })
}

module.exports = saveNewUser

компонент, который я пытаюсь использовать в

import {useState} from 'react'
import Layout from "../components/Layout";
import Card from "../components/Card";
import Button from "../components/Button";
import Logo from "../components/Logo";
import Background from "../components/Background";
import Header from "../components/Header";
import TextContent from "../components/TextContent";
import EmailInput from "../components/EmailInput";
import FormGroup from "../components/FormGroup";
import saveNewUser from "../utils/saveNewUser"

const generateNewKey = (props) => {

  const [email, setEmail] = useState("");

  const onSubmit = e => {
    e.preventDefault()
    if (email === ''){
      console.log('Please enter something')
    }
    saveNewUser(email)
  }

  const emailInputOnChange = e =>{ 
    setEmail(e.target.value)
  };

    return (
        <React.Fragment>
            <Layout />
            <Background />
            <Card>
                <Logo />
                <Header text='Air Stats API' />
                <TextContent>
                    To generate a new API key all we need is your name and email
                </TextContent>
                <FormGroup onSubmit = {onSubmit}>
                    <EmailInput
                        placeholder='Email'
            for='email'
            onChange={emailInputOnChange}
                    ></EmailInput>
                    <Button
                        text='Get API Key'
                        width='25%'
            type="submit"
                    ></Button>
                </FormGroup>
            </Card>
        </React.Fragment>
    );
};

export default generateNewKey;

Мой сервер. js

const express = require('express');
const mongoose = require('mongoose');
const cors = require('cors');
const morgan = require('morgan');
const helmet = require('helmet');
const dotenv = require('dotenv').config();
const apiRouter = require('./routes/ApiRouter');

function connectToDB() {
  mongoose.connect(process.env.URI, {
    useNewUrlParser: true,
    useUnifiedTopology: true,
    dbName: 'AircraftCharacteristics'
  });

  const db = mongoose.connection;
  db.on('error', console.error.bind(console, 'connection error:'));
  db.once('open', () => {
    console.log('Connected to DB');
  });
}

const loadMiddleware = () => {
  // Cross origin resource sharing middleware
  app.use(
    cors({
      origin: ['http://localhost:3000'],
      methods: ['GET', 'POST'],
      allowedHeaders: ['Content-Type', 'Authorization']
    })
  );

  // Security middleware
  app.use(helmet());

  // Morgan set to log all requests
  app.use(morgan('common'));

  // API router
  app.use('/api', apiRouter);

  console.log('Middleware Loaded');
};

const startServer = () => {
  app.listen(port, () => console.log(`App listening on ${port}`));
};

const app = express();
const port = process.env.PORT;

startServer();
loadMiddleware();
connectToDB();