I've been investigating issues some Remix users have had since we migrated from esbuild-plugin-polyfill-node.

One issue is that the fs polyfill is throwing an error when building for Cloudflare since it sets up a file system watcher as a top-level side effect:

service core:user:worker: Uncaught Error: Some functionality, such as asynchronous I/O, timeouts, and generating random values, can only be performed while handling a request.

What's interesting is this wasn't happening with our old polyfill setup even though it was also built on JSPM browser polyfills. It turns out that previously the fs polyfill was actually an empty module by default (among others): https://github.com/cyco130/esbuild-plugin-polyfill-node/blob/9afcb6abaf9062a15daaffce9a14e478b365139c/src/index.ts#L143-L149. I can reproduce the same error with our old polyfills if I explicitly enable the fs polyfill.

In order to support this scenario, this PR extends the modules option to support an object that can optionally configure empty polyfills, e.g.

nodeModulesPolyfillPlugin({
  modules: {
    fs: 'empty',
    crypto: true,
  }
})

Status and versioning classification:

• Code changes have been tested and working fine, or there are no code changes
• This PR changes the library's interface (methods or parameters added)