Gulp Невозможно преобразовать неопределенный или нулевой объект

Question

my gulpfile.js содержит ff:

'use strict'

// All add-ons required
const gulp = require('gulp')
const uglify = require('gulp-uglify')
const sourcemaps = require('gulp-sourcemaps')
const csso = require('gulp-csso')
const htmlmin = require('gulp-htmlmin')
const concat = require('gulp-concat')
const rename = require('gulp-rename')
const del = require('del')

// Tasks

// Minifies HTML
gulp.task('pages', function() {
  return gulp.src('src/*.html')
    .pipe(htmlmin({ collapseWhitespace: true, ignoreCustomComments: '[ /!/ ]', removeComments: true }))
    .pipe(gulp.dest('./dist/'))
})

// Copy NPM frameworks to vendor/
gulp.task('vendor', function() {
  return gulp.src(['./node_modules/materialize-css/dist/css/materialize.min.css', './node_modules/materialize-css/dist/js/materialize.min.js'], { base: 'node_modules' })
    .pipe(gulp.dest('./dist/vendor/'))
})

// Minifies CSS
gulp.task('styles', function() {
  return gulp.src('./src/assets/styles/*.css')
    .pipe(sourcemaps.init())
  // Minify the file
    .pipe(csso())
  // Concatenate all CSS files to 'styles.min.css' then Output
    .pipe(concat('design'))
    .pipe(rename({ suffix: '.min.css' }))
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest('./dist/css/'))
})

// Minifies JS Files
gulp.task('scripts', function() {
  return gulp.src('./src/assets/js/*.js')
  // Create a sourcemap
    .pipe(sourcemaps.init())
  // Minify the file
    .pipe(uglify())
  // Concatenate all js files to 'app.min.js' then Output
    .pipe(concat('asset'))
    .pipe(rename({ suffix: '.min.js' }))
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest('./dist/js/'))
})

// Minifies the main Renderer file `main.js`
gulp.task('renderer', function() {
  return gulp.src('./src/main.js')
  // Create a sourcemap
    .pipe(sourcemaps.init())
  // Minify the file
    .pipe(uglify())
  // Concatenate all js files to 'app.min.js' then Output
    .pipe(concat('app'))
    .pipe(rename({ suffix: '.min.js' }))
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest('./dist/'))
})

// Cleans the dist/ folder if not empty
// to avoid conflicts per gulp runs
gulp.task('clean', function() {
  return gulp.src('dist/*')
    .pipe(del('./dist/*'))
})

// Default Build
gulp.task('default',
  gulp.series('clean', gulp.parallel('pages', 'vendor', 'styles', 'scripts', 'renderer')))

каждый раз, когда я запускаю gulp или gulp [task], это просто выдает некоторые ошибки, которые не имеют смысла для меня:

[19:43:57] Using gulpfile ~\Desktop\LAN\Workspace\Code\secret [revamp]\gulpfile.js
C:\Users\Admin\AppData\Roaming\npm\node_modules\gulp\lib\taskTree.js:4
  return Object.keys(tasks)
                ^

TypeError: Cannot convert undefined or null to object
    at Function.keys (<anonymous>)
    at module.exports (C:\Users\Admin\AppData\Roaming\npm\node_modules\gulp\lib\taskTree.js:4:17)
    at logTasks (C:\Users\Admin\AppData\Roaming\npm\node_modules\gulp\bin\gulp.js:134:14)
    at C:\Users\Admin\AppData\Roaming\npm\node_modules\gulp\bin\gulp.js:127:14
    at internalTickCallback (internal/process/next_tick.js:70:11)
    at process._tickCallback (internal/process/next_tick.js:47:5)
    at Function.Module.runMain (internal/modules/cjs/loader.js:763:11)
    at startup (internal/bootstrap/node.js:303:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:872:3)

Уже пробовал это решение , но, к несчастью, у меня не получилось.

P.S
моя gulp версия "gulp": "^4.0.0"