Webpackでgsapのプラグインをcdn化したい。

Question

webpackのexternalsを使って、typescriptファイル内でインポートしているgsapをcdn化したいのですが、chromeのコンソールに次のようなエラーが出てしまいます。
どのように対処したらよいのでしょうか。

webpackは4.42.1、gsapは3.2.6を使用しています。

CSSPlugin.js:12 Uncaught SyntaxError: Cannot use import statement outside a module
PixiPlugin.js:367 Uncaught SyntaxError: Unexpected token 'export'

import gsap from "gsap";
import PixiPlugin from "gsap/PixiPlugin";
import CSSPlugin from "gsap/CSSPlugin";

const plugins = [PixiPlugin, CSSPlugin];
gsap.registerPlugin(plugins);
export default gsap;

{
  "compilerOptions": {
    "target": "es5",
    "module": "es6",
    "lib": ["dom", "esnext"],
    "baseUrl": "./src/ts",
    "outDir": "./dist/js",
    "sourceMap": false,
    "allowJs": true,
    "alwaysStrict": true,
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "isolatedModules": true,
    "moduleResolution": "node",
    "noEmit": false,
    "noFallthroughCasesInSwitch": true,
    "noUnusedLocals": false,
    "noUnusedParameters": false,
    "removeComments": true,
    "skipLibCheck": true,
    "strict": true,
    "noImplicitAny": false,
    "strictNullChecks": false
  },
  "compileOnSave": true,
  "include": [
    "src/ts/**/*.ts"
  ],
  "exclude": [
    "node_modules",
  ],
}

const path = require("path");
const WebpackCdnPlugin = require('webpack-cdn-plugin');

module.exports = {

  entry: {
    app: "./src/index.ts"
  },

  // 出力先
  output: {
    filename: "js/[name].js",
    path: path.join(__dirname, "dist"),
    libraryTarget: "umd"
  },

  module: {
    rules: [{
        test: /.js$/,
        use: "babel-loader",
        exclude: /node_modules/
      }, {
        test: /.ts$/,
        use: "ts-loader",
        exclude: /node_modules/
      }
    ]
  },

  optimization: {
    usedExports: true,
    splitChunks: {
      cacheGroups: {
        vendor: {
          test: /node_modules/,
          name: "vendor",
          chunks: "initial",
        }
      }
    }
  },

  resolve: {
    extensions: [".ts", ".js"],
  },
  plugins: [
    new WebpackCdnPlugin({
      modules: [{
          name: 'pixi.js',
          var: 'PIXI',
          path: 'dist/pixi.min.js'
        },
        {
          name: 'gsap',
          path: 'dist/gsap.min.js'
        },
        {
          name: 'gsap',
          path: 'CSSPlugin.js'
        },
        {
          name: 'gsap',
          path: 'PixiPlugin.js'
        }
      ],
      publicPath: '/node_modules'
    })
  ],
  externals: [{
      "pixi.js": "PIXI",
      "gsap": "gsap",
      "gsap/CSSPlugin": "CSSPlugin",
      "gsap/PixiPlugin": "PixiPlugin"
    },
  ]
};