jszip is not a constructor

[Jude214]

on version 0.8.13，the brower reports such an error when export a file:

this is caused by code in xlsx.js:

we need to replace the code above with this:
if(typeof jszip === 'undefined') jszip = require('./jszip.js');

[iyu98]

const NodePolyfillPlugin = require("node-polyfill-webpack-plugin")
 
module.exports = defineConfig({
  configureWebpack: {
    plugins: [
        new NodePolyfillPlugin()
      ]
    }
})