package.json

...
"plugins": [
        [
          "@electron-forge/plugin-webpack",
          {
            "mainConfig": "./webpack.main.config.js",
            "renderer": {
              "config": "./webpack.renderer.config.js",
              "entryPoints": [
                {
                  "html": "./src/renderer/html/index.html",
                  "js": "./src/renderer/js/index.js",
                  "name": "main_window"
                }
              ]
            }
          }
        ]
      ]
...

webpack.main.config.js

module.exports = {
  /**
   * This is the main entry point for your application, it's the first file
   * that runs in the main process.
   */
  entry: './src/main.js',
  // Put your normal webpack config below here
  module: {
    rules: require('./webpack.rules'),
  },
};

webpack.renderer.config.js

module.exports = {
  // Put your normal webpack config below here
  module: {
    rules: require('./webpack.rules'),
  },
};

webpack.rules.js

module.exports = [
  // Add support for native node modules
  {
    test: /\.node$/,
    use: 'node-loader',
  },
  {
    test: /\.(m?js|node)$/,
    parser: { amd: false },
    use: {
      loader: '@marshallofsound/webpack-asset-relocator-loader',
      options: {
        outputAssetBase: 'native_modules',
      },
    },
  }
];