Webpackconfig che non vuole saperne

Buongiorno..ho questo webpackconfig.js 

import { resolve as _resolve } from 'path';  
    export const entry = {
   app: './src/testrx.js'
};
export const resolve = {
   extensions: ['', '.js', '.jsx']
};
export const output = {
   path: _resolve(__dirname, 'dev'),
   filename: 'main_bundle.js'
};
export const mode = 'development';
export const module = {
   rules: [
      {
         test: /\.(js)$/,
         include: _resolve(__dirname, 'src'),
         loader: 'babel-loader',
         options: {
            presets: ['@babel/preset-env']
         }
      }
   ]
};  

ma quando faccio il build mi da questo errore

[webpack-cli] Failed to load 'C:\PrjtestRSJX\webpack.config.js' config
[webpack-cli] ReferenceError: __dirname is not defined in ES module scope
This file is being treated as an ES module because it has a '.js' file extension and 'C:\PrjtestRSJX\package.json' contains "type": "module". To treat it as a CommonJS script, rename it to use the '.cjs' file extension.      
   at file:///C:/PrjtestRSJX/webpack.config.js:9:19

Potete aiutarmi? cosa sbaglio?