I'm using NodeJS, PassportJS, MySQL, and Sequalize(ORM for MySQL). This code is from my Passport.JS file. When a user registers on my website if the username or email is taken I will return an error. If both username, email can't be found in database a new create account will be created.

The error I'm getting when I register on my website is...

Unhandled rejection TypeError: Cannot read property 'username' of null

    at null.<anonymous> (/home/ubuntu/workspace/Authentication.1/config/passport/passport.js:50:16)

    at tryCatcher (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/util.js:16:23)

    at Promise._settlePromiseFromHandler (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:512:31)

    at Promise._settlePromise (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:569:18)

    at Promise._settlePromise0 (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:614:10)

    at Promise._settlePromises (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/promise.js:693:18)

    at Async._drainQueue (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/async.js:133:16)

    at Async._drainQueues (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/async.js:143:10)

    at Immediate.Async.drainQueues [as _onImmediate] (/home/ubuntu/workspace/Authentication.1/node_modules/sequelize/node_modules/bluebird/js/release/async.js:17:14)

My code is:

        User.findOne({

            // SELECT * FROM users WHERE username = username || email = ... 

            where: {

                $or: [{username: username}, {email: req.body.email}]

            }

        }).then(function(user){



        // GETTING ERROR HERE. If username is already in database

        if(user.username !== null && user.username == req.body.username) {

          return done(null, false, console.log(USER TAKEN),{message : 'That username is already taken'} );

        }



        // If email is already in database return err.

        else if(user.email !== null && user.email == req.body.email) {

          return done(null, false, console.log(EMAIL TAKEN),{message : 'That email is already taken'} );

        }



        else [code for create new account]...