Return value is undefined

Question

Node Route:

exports.addUser = async ( req, res, next ) => {
    const name = req.body.name;
    const email = req.body.email;
    const password = req.body.password;

    const unique = await User.isUserUnique( email );
    console.log( unique );

    bcrypt.hash( password, 10, function ( err, hash ) {
        const user = new User( name, email, hash );
        //user.saveUser();
    } );


    res.send( req.body );
};

Model:

const client = require( "../database/index" );

class User {
    constructor( name, email, password ) {
        this.name = name;
        this.email = email;
        this.password = password;
    }

    static isUserUnique( email ) {
        return client.connect( () => {
            return client.db( "alliance" ).collection( "users" ).findOne( { email } ).then( ( user ) => {
                return user;
            } );
        } );
    }

Database:

const MongoClient = require( "mongodb" ).MongoClient;

const client = new MongoClient( url );

client.connect( function ( err ) {

    if ( err ) {
        console.log( err );
    }

    console.log( "Connected successfully to server" );

} );

module.exports = client;

Why is the unique constant that i declare in the Node Route undefined? Does it have something to do with the "return client.connect(())"? Basically I want the static method to return the user, so I assumed all you have to do inside of the Static method was return every value so they go up to the parent that called it, and then I would get it on the called constant. I have done something similair, except this time it is with connect method as the surrounding parent.