Gulp build ошибка при сборке

var gulp           = require('gulp'), 
		gutil          = require('gulp-util' ), 
		sass           = require('gulp-sass'), 
		browserSync    = require('browser-sync'), 
		concat         = require('gulp-concat'), 
		uglify         = require('gulp-uglify'), 
		cleanCSS       = require('gulp-clean-css'), 
		rename         = require('gulp-rename'), 
		del            = require('del'), 
		imagemin       = require('gulp-imagemin'), 
		cache          = require('gulp-cache'), 
		autoprefixer   = require('gulp-autoprefixer'), 
		ftp            = require('vinyl-ftp'), 
		notify         = require("gulp-notify"), 
		rsync          = require('gulp-rsync'); 
 
	gulp.task('browser-sync', function() { 
		browserSync({ 
			server: { 
				baseDir: 'app' 
			}, 
			notify: false, 
			// tunnel: true, 
			// tunnel: "projectmane", //Demonstration page: http://projectmane.localtunnel.me 
		}); 
	}); 
 
// Пользовательские скрипты проекта 
 
gulp.task('common-js', function() { 
	return gulp.src([ 
		'app/js/common.js', 
		]) 
	.pipe(concat('common.min.js')) 
	.pipe(uglify()) 
	.pipe(gulp.dest('app/js')); 
}); 
 
gulp.task('js', ['common-js'], function() { 
	return gulp.src([ 
		'app/libs/jquery/dist/jquery.min.js', 
		// 'app/libs/owlcarousel/js/owl.carousel.min.js', 
		'app/js/common.min.js', // Всегда в конце 
		]) 
	.pipe(concat('scripts.min.js')) 
	// .pipe(uglify()) // Минимизировать весь js (на выбор) 
	.pipe(gulp.dest('app/js')) 
	.pipe(browserSync.reload({ stream: true })); 
}); 
 
gulp.task('sass', function() { 
	return gulp.src('app/sass/**/*.sass') 
	.pipe(sass({outputStyle: 'expanded'}).on("error", notify.onError())) 
	.pipe(rename({suffix: '.min', prefix : ''})) 
	.pipe(autoprefixer(['last 15 versions'])) 
	//.pipe(cleanCSS()) // Опционально, закомментировать при отладке 
	.pipe(gulp.dest('app/css')) 
	.pipe(browserSync.stream()) 
}); 
 
gulp.task('watch', ['sass', 'js', 'browser-sync'], function() { 
	gulp.watch('app/sass/**/*.sass', ['sass']); 
	gulp.watch(['libs/**/*.js', 'app/js/common.js'], ['js']); 
	gulp.watch('app/*.html', browserSync.reload); 
}); 
 
gulp.task('imagemin', function() { 
	return gulp.src('app/img/**/*') 
	.pipe(cache(imagemin())) // Cache Images 
	.pipe(gulp.dest('dist/img'));  
}); 
 
gulp.task('build', ['removedist', 'imagemin', 'sass', 'js'], function() { 
 
	var buildFiles = gulp.src([ 
		'app/*.html', 
		'app/.htaccess', 
		]).pipe(gulp.dest('dist')); 
 
	var buildCss = gulp.src([ 
		'app/css/main.min.css', 
		]).pipe(gulp.dest('dist/css')); 
 
	var buildJs = gulp.src([ 
		'app/js/scripts.min.js', 
		]).pipe(gulp.dest('dist/js')); 
 
	var buildFonts = gulp.src([ 
		'app/fonts/**/*', 
		]).pipe(gulp.dest('dist/fonts')); 
 
}); 
 
gulp.task('deploy', function() { 
 
	var conn = ftp.create({ 
		host:      'hostname.com', 
		user:      'username', 
		password:  'userpassword', 
		parallel:  10, 
		log: gutil.log 
	}); 
 
	var globs = [ 
	'dist/**', 
	'dist/.htaccess', 
	]; 
	return gulp.src(globs, {buffer: false}) 
	.pipe(conn.dest('/path/to/folder/on/server')); 
 
}); 
 
gulp.task('rsync', function() { 
	return gulp.src('dist/**') 
	.pipe(rsync({ 
		root: 'dist/', 
		hostname: 'username@yousite.com', 
		destination: 'yousite/public_html/', 
		// include: ['*.htaccess'], // Скрытые файлы, которые необходимо включить в деплой 
		recursive: true, 
		archive: true, 
		silent: false, 
		compress: true 
	})); 
}); 
 
gulp.task('removedist', function() { return del.sync('dist'); }); 
gulp.task('clearcache', function () { return cache.clearAll(); }); 
 
gulp.task('default', ['watch']);