How can I fix this code?

import mongoose from 'mongoose';

import 'dotenv$/$config$\text{'}$;

const USER$\_$DB$\_$NAME $=$ 'Users$\_$db$\text{'}$;

const USER$\_$COLLECTION $=$ 'users';

const USER$\_$CLASS $=$ 'User';

let connection $=$ undefined;

let User $=$ undefined;

$/**$

$*$ This function connects to the MongoDB server.

$*/$

async function connect$()\{$

$$ try$\{$

$$ await mongoose.connect$($process$.$env.MONGODB$\_$CONNECT$\_$STRING$)$;

$$ connection $=$ mongoose.connection;

$$ console.log$("$Successfully connected to MongoDB using Mongoose!"$)$;

$$ if$($dropCollection$)\{$

$$ await connection.db$.$dropCollection$($USER$\_$COLLECTION$)$;

$\}$

$$ User $=$ createModel$()$;

$\}$ catch$($err$)\{$

$$ console.log$($err$)$;

$$ throw Error$(`$Could not connect to MongoDB $$\{$err$.$message$\}`)$

$\}$

$\}$

function createModel$()\{$

$$ const userSchema $=$ mongoose.Schema$(\{$

$$ name: $\{$type: String, required: true$\},$

$$ age: $\{$type: Number, required: true$\},$

$$ email: $\{$type: String, required: true$\},$

$$ phoneNumber: $\{$type: Number, required: false$\},$

$\})$;

$$ return mongoose.model$($USER$\_$CLASS, userSchema$)$;

$\}$

async function createUser$($name$,$ age, email, phoneNumber$)\{$

$$ const user $=$ new User$(\{$name: name, age: age, email: email, phoneNumber: phoneNumber$\})$;

$$ return user.save$()$; $$

$\}$

async function findUsers$($filter$)\{$

$$ const query $=$ User.find$($filter$)$;

$$ return query.exec$()$;

$\}$

async function findUserById$(\_$id$)\{$

$$ const user $=$ await User.findById$(\_$id$)$;

$$ return user.exec$()$;

$\}$

async function updateUser$(\_$id$,$ updates$)\{$

$$ try $\{$

$//$ Ensure $`$updates$`$ only contains valid fields for the schema

$$ const allowedFields $=[\text{'}$name$\text{'},$ 'age', 'email', 'phoneNumber'$]$;

$$ const filteredUpdates $=\{\}$;

$$ Object.keys$($updates$).$forEach$(($key$)=>\{$

$$ if $($allowedFields$.$includes$($key$)$ && updates$[$key$]!==$ undefined$)\{$

$$ filteredUpdates$[$key$]=$ updates$[$key$]$;

$\}$

$\})$;

$$ if $($Object$.$keys$($filteredUpdates$).$length $===0)\{$

$$ throw new Error$("$No valid fields to update"$)$;

$\}$

$//$ Use updateOne to apply the updates

$$ const result $=$ await User.updateOne$($

$\{\_$id: $\_$id $\},$

$\{$ $set: filteredUpdates $\},//$ Use $set to update specific fields

$\{$ runValidators: true $\}//$ Ensure updates adhere to the schema's validation rules

$)$;

$$ if $($result$.$matchedCount $===0)\{$

$$ throw new Error$("$Not found"$)$;

$\}$

$//$ Return the updated document $($requires an additional query$)$

$$ const updatedUser $=$ await User.findById$(\_$id$)$;

$$ return updatedUser;

$\}$ catch $($error$)\{$

$$ throw new Error$($error$.$message$)$;

$\}$

$\}$

async function deleteUsers$($query$)\{$

$$ try $\{$

$//$ Delete users based on the provided query

$$ const result $=$ await User.deleteMany$($query$)$;

$//$ Return the count of deleted documents

$$ return $\{$ deletedCount: result.deletedCount $\}$;

$\}$ catch $($error$)\{$

$$ throw new Error$(`$Error deleting users: $$\{$error$.$message$\}`)$;

$\}$

$\}$

const deleteById $=$ async $(\_$id$)=>\{$

$$ const result $=$ await User.deleteOne$(\{\_$id: $\_$id $\})$;

$$ return result.deletedCount;

$\}$

export $\{$ connect, createUser, findUsers, findUserById, updateUser, deleteUsers, deleteById $\}$;

These are the directions:

Introduction

In this assignment, you will write a REST API for a collection of users. The REST API will store its data in MongoDB and will use Mongoose for interacting with MongoDB.

Instructions

Write a REST API that models a user and provides CRUD operations listed below.

You must write code in the files users$\_$model.mjs and users$\_$controller.mjs to implement the REST API.$$Do not change any other files we have provided you in the starter code and do not add any new files to your app.

The user collection in MongoDB must be named users.

Your model code must be separate from your controller code.

The controller code must not directly call any Mongoose code, but can only interact with the database by calling functions exported by your model code. You cannot import the Mongoose package in the controller.You cannot import the express package in your model. You cannot pass any Express objects $($e$.$g$.,$ request and response$)$ to functions in your model.$$You cannot export the model class $($by default, Users$)$ from your model.

Your code must use the async and await syntax for asynchronous programming and cannot use the $.$then$()$ syntax.

The route handler functions in the controller will be asynchronous. You must wrap these functions inside asyncHandler to prevent your Express server from crashing due to any uncaught exception.

$1.$ Create using POST $/$users

Request

Path parameter: None.Body: The body will be a JSON object with the following properties. You can assume that the body of a POST request will always be valid.

Response

Body: A JSON object with all properties of the newly created user, including $\_$id$.$Content$-$type: application$/$json$.$Status code: $201.$