google-auth-library token_id check

googleAuth.js

const credentials = require( './credentials.json' )
const GOOGLE_CLIENT_ID = credentials.google.client_id;
const { OAuth2Client } = require( 'google-auth-library' );
var client = new OAuth2Client( GOOGLE_CLIENT_ID, '', '' );

//return a promise with user informations
module.exports.getGoogleUser = ( code ) => {
    //verify the token using google client
    return client.verifyIdToken( { idToken: code, audience: GOOGLE_CLIENT_ID } )
        .then( login => {
            //if verification is ok, google returns a jwt
            var payload = login.getPayload();
            var userid = payload['sub'];

            //check if the jwt is issued for our client
            var audience = payload.aud;
            if ( audience !== GOOGLE_CLIENT_ID ) {
                throw new Error( "error while authenticating google user: audience mismatch: wanted [" + GOOGLE_CLIENT_ID + "] but was [" + audience + "]" )
            }
            //promise the creation of a user
            return {
                name: payload['name'], //profile name
                pic: payload['picture'], //profile pic
                id: payload['sub'], //google id
                email_verified: payload['email_verified'], 
                email: payload['email']
            }
        } )
        .then( user => { return user; } )
        .catch( err => {
        //throw an error if something gos wrong
            throw new Error( "error while authenticating google user: " + JSON.stringify( err ) );
        } )
}