terser-webpack-plugin with Next.js + Webpack 4

[fatihtelis]

Summary

I'm using Next.js with Webpack 4 and when I add a fallback page to pages/_offline, terser-webpack-plugin gives the error below:

TypeError: Cannot read property 'javascript' of undefined
at /Users/xxxxxxxxx/node_modules/terser-webpack-plugin/dist/index.js:572:38

I searched for the issue and terser-webpack-plugin@5+ is for Webpack 5 and is not compatible with Webpack 4.

How To Reproduce

Steps to reproduce the behavior:

1. Use next-pwa@5.2.9 which has a dependency for terser-webpack-plugin: "^5.1.1" (Only compatible with Webpack 5)
2. Use next.js with Webpack 4
3. Add a fallback page to pages/_offline.js
4. Get error while building the app.

[shadowwalker]

Unfortunately this is a unsolvable problem, if I don't add terser-webpack-plugin as dependency in next-pwa. Other folks will see another build error.
Can you try to use {future: webpack5: true} in your project or try install the lower version of terser-webpack-plugin by yarn install terser-webpack-plugin@4.2.3 to mitigate the issue you have encountered?

[fatihtelis]

I upgraded to Webpack 5. It is working properly now. Thanks for the reply @shadowwalker.

[quick007]

You now just use webpack5: true, in the nextjs config