In My Gulpfile.js faulty part:

gulp.task('webpack', gulp.series(async () => {

    const option = yargs.argv.release ? -p : -d;

    execSync(`node_modules/webpack-cli/bin/cli.js ${option}`, {

        stdio: [null, process.stdout, process.stderr]

    });

}));

My package.json:

{

  scripts: {

    postinstall: npm run package-dev,

    package-dev: node ./node_modules/gulp/bin/gulp.js,

    package-release: node ./node_modules/gulp/bin/gulp.js --release

  },

  Dependencies: {

    @types/applicationinsights-js: ^1.0.5,

    @types/jquery: ^2.0.41,

    @types/knockout: ^3.4.40,

    @types/react: ^16.0.40,

    @types/react-dom: ^16.9.1,

    @types/requirejs: ^2.1.28,

    del: ^3.0.0,

    gulp: ^4.0.2,

    gulp-inline-source: ^4.0.0,

    gulp-sass: ^4.0.2,

    gulp-tslint: ^8.1.1,

    office-ui-fabric-react: ^4.5.0,

    promise-polyfill: ^8.1.0,

    requirejs: ^2.3.2,

    ts-loader: ^4.1.0,

    tslint: ^5.4.3,

    typescript: ^3.1.6,

    vss-web-extension-sdk: ^5.141.0,

    webpack: ^4.26.1,

    webpack-cli: ^3.1.2

  },

  name: task-group,

  private: true,

  version: 0.7.0,

  dependencies: {

    @uifabric/utilities: ^7.2.0,

    react: ^16.9.0

  },

  main: gulpfile.js,

  keywords: [],

  author: ,

  license: ISC,

  description: 

}

I running npm install and get the following error.

In Terminal Screen:

gulp.task('webpack', gulp.series(async () => {
^
SyntaxError: Unexpected token (
at Object.exports.runInThisContext (vm.js:76:16)
at Module._compile (module.js:542:28)
at Object.Module._extensions..js (module.js:579:10)
at Module.load (module.js:487:32)
at tryModuleLoad (module.js:446:12)
at Function.Module._load (module.js:438:3)
at Module.require (module.js:497:17)
at require (internal/module.js:20:19)
at execute (C:UsersEceDocumentsProjectsLinks-Groupnode_modulesgulpnode_modulesgulp-clilibversioned^4.0.0index
.js:36:18)
at Liftoff.handleArguments (C:UsersEceDocumentsProjectsLinks-Groupnode_modulesgulpnode_modulesgulp-cliindex.js:2
01:24)