gulp errors handle

var notify = require('gulp-notify');

function log() {
    var args = Array.prototype.slice.call(arguments);
    // Send error to notification center with gulp-notify
    notify.onError({
        title: 'Compile Error',
        message: '<%= error %>'
    }).apply(this, args);

    // Keep gulp from hanging on this task
    this.emit('end');
};

gulp.task('test:css', function () {
    return gulp.src(css)
        .pipe(postcss([
            require('stylelint')(config),
            require('postcss-reporter')({
                clearMessages: true,
            }),
        ]))
        .on('error', log);