gulpfile.js

// bundles our code for prod
gulp.task('bundle', function(cb) {
    builder.loadConfig('./client/src/app/system.config.js').then(function(response) {
        builder.build('./client/src/app/app.module', './client/build/bundle.js').then(function(build) {
            console.log('done');
            cb();
        });
    });
});