Компиляция. GULP. JS. Верстка. Ошибка при сборе

"use strict";

const {src, dest} = require("gulp");
const gulp = require("gulp");
const autoprefixer = require("gulp-autoprefixer");
const cssbeautify = require("gulp-cssbeautify");
const removeComments = require('gulp-strip-css-comments');
const rename = require("gulp-rename");
const sass = require("gulp-sass")(require("sass"));
const cssnano = require("gulp-cssnano");
const uglify = require("gulp-uglify");
const plumber = require("gulp-plumber");
const panini = require("panini");
const imagemin = require("gulp-imagemin");
const del = require("del");
const notify = require("gulp-notify");
const webpack = require('webpack');
const webpackStream = require('webpack-stream');
const browserSync = require("browser-sync").create();

// папки для всех файлов 
// основные папки
/* Paths */
const srcPath = 'src/';
const distPath = 'dist/';
// точный сбор по папкам
const path = {
    build: {
        html:   distPath,
        js:     distPath + "assets/js/",
        css:    distPath + "assets/css/",
        images: distPath + "assets/images/",
        fonts:  distPath + "assets/fonts/"
    },
    src: {
        html:   srcPath + "*.html",
        js:     srcPath + "assets/js/*.js",
        css:    srcPath + "assets/scss/*.scss",
        images: srcPath + "assets/images/**/*.{jpg,png,svg,gif,ico,webp,webmanifest,xml,json}",
        fonts:  srcPath + "assets/fonts/**/*.{eot,woff,woff2,ttf,svg}"
    },
    watch: {
        html:   srcPath + "**/*.html",
        js:     srcPath + "assets/js/**/*.js",
        css:    srcPath + "assets/scss/**/*.scss",
        images: srcPath + "assets/images/**/*.{jpg,png,svg,gif,ico,webp,webmanifest,xml,json}",
        fonts:  srcPath + "assets/fonts/**/*.{eot,woff,woff2,ttf,svg}"
    },
    clean: "./" + distPath
}



/* Tasks */
// Таски для лок. сервера
function serve() {
    browserSync.init({
        server: {
            baseDir: "./" + distPath
        }
    });
}
// разбитие и сбор HTML
function html(cb) {
    panini.refresh();
    return src(path.src.html, {base: srcPath})
        .pipe(plumber())
        .pipe(panini({
            root:       srcPath,
            layouts:    srcPath + 'layouts/',
            partials:   srcPath + 'partials/',
            helpers:    srcPath + 'helpers/',
            data:       srcPath + 'data/'
        }))
        .pipe(dest(path.build.html))
        .pipe(browserSync.reload({stream: true}));

    cb();
}
// Слежка за ощибками
function css(cb) {
    return src(path.src.css, {base: srcPath + "assets/scss/"})
        .pipe(plumber({
            errorHandler : function(err) {
                notify.onError({
                    title:    "SCSS Error",
                    message:  "Error: <%= error.message %>"
                })(err);
                this.emit('end');
            }
        }))
        .pipe(sass({
            includePaths: './node_modules/'
        }))
        .pipe(autoprefixer({
            cascade: true
        }))
        .pipe(cssbeautify())
        .pipe(dest(path.build.css))
        .pipe(cssnano({
            zindex: false,
            discardComments: {
                removeAll: true
            }
        }))
        .pipe(removeComments())
        .pipe(rename({
            suffix: ".min",
            extname: ".css"
        }))
        .pipe(dest(path.build.css))
        .pipe(browserSync.reload({stream: true}));

    cb();
}
// убираем лишнее, что бы во время разработки сайта все работало быстрее 
function cssWatch(cb) {
    return src(path.src.css, {base: srcPath + "assets/scss/"})
        .pipe(plumber({
            errorHandler : function(err) {
                notify.onError({
                    title:    "SCSS Error",
                    message:  "Error: <%= error.message %>"
                })(err);
                this.emit('end');
            }
        }))
        .pipe(sass({
            includePaths: './node_modules/'
        }))
        .pipe(rename({
            suffix: ".min",
            extname: ".css"
        }))
        .pipe(dest(path.build.css))
        .pipe(browserSync.reload({stream: true}));

    cb();
}
// таск для Js файлов
function js(cb) {
    return src(path.src.js, {base: srcPath + 'assets/js/'})
        .pipe(plumber({
            errorHandler : function(err) {
                notify.onError({
                    title:    "JS Error",
                    message:  "Error: <%= error.message %>"
                })(err);
                this.emit('end');
            }
        }))
        .pipe(webpackStream({
          mode: "production",
          output: {
            filename: 'app.js',
          },
          module: {
            rules: [
              {
                test: /\.(js)$/,
                exclude: /(node_modules)/,
                loader: 'babel-loader',
                query: {
                  presets: ['@babel/preset-env']
                }
              }
            ]
          }
        }))
        .pipe(dest(path.build.js))
        .pipe(browserSync.reload({stream: true}));

    cb();
}
// по аналогии с CSS. jsWatch убираем лишьнее, что бы при работе все работало быстро
function jsWatch(cb) {
    return src(path.src.js, {base: srcPath + 'assets/js/'})
        .pipe(plumber({
            errorHandler : function(err) {
                notify.onError({
                    title:    "JS Error",
                    message:  "Error: <%= error.message %>"
                })(err);
                this.emit('end');
            }
        }))
        .pipe(webpackStream({
          mode: "development",
          output: {
            filename: 'app.js',
          }
        }))
        .pipe(dest(path.build.js))
        .pipe(browserSync.reload({stream: true}));

    cb();
}
// сжатие картинок и их оптимизация 
function images(cb) {
    return src(path.src.images)
        .pipe(imagemin([
            imagemin.gifsicle({interlaced: true}),
            imagemin.mozjpeg({quality: 95, progressive: true}),
            imagemin.optipng({optimizationLevel: 5}),
            imagemin.svgo({
                plugins: [
                    { removeViewBox: true },
                    { cleanupIDs: false }
                ]
            })
        ]))
        .pipe(dest(path.build.images))
        .pipe(browserSync.reload({stream: true}));

    cb();
}
// шрифты
function fonts(cb) {
    return src(path.src.fonts)
        .pipe(dest(path.build.fonts))
        .pipe(browserSync.reload({stream: true}));

    cb();
}

function clean(cb) {
    return del(path.clean);

    cb();
}
// какие таски будем выполнять для слежки за файлами 
function watchFiles() {
    gulp.watch([path.watch.html], html);
    gulp.watch([path.watch.css], cssWatch);
    gulp.watch([path.watch.js], jsWatch);
    gulp.watch([path.watch.images], images);
    gulp.watch([path.watch.fonts], fonts);
}

const build = gulp.series(clean, gulp.parallel(html, css, js, images, fonts));
const watch = gulp.parallel(build, watchFiles, serve);



/* Exports Tasks */
exports.html = html;
exports.css = css;
exports.js = js;
exports.images = images;
exports.fonts = fonts;
exports.clean = clean;
exports.build = build;
exports.watch = watch;
exports.default = watch;