Kotlin/JS-modules no longer work in browser after #256

[fzhinkin]

In #256 I refactored the interop with nodeJs modules providing filesystem support. If previously, only functionality related to files and filesystem didn't work in a browser (with UnsupportedOperationException being thrown), now an attempt to use anything declared in kotlinx-io-core leads to errors like this:

> Task :gradle-core-multiplatform:jsBrowserTest
Module not found: Error: Can't resolve 'buffer' in '/Users/Filipp.Zhinkin/Development/kotlinx-io-release-tests/build/js/packages/kotlinx-io-release-tests-gradle-core-multiplatform-test/kotlin'

BREAKING CHANGE: webpack < 5 used to include polyfills for node.js core modules by default.
This is no longer the case. Verify if you need this module and configure a polyfill for it.

If you want to include a polyfill, you need to:
        - add a fallback 'resolve.fallback: { "buffer": require.resolve("buffer/") }'
        - install 'buffer'
If you don't want to include a polyfill, you can use an empty module like this:
        resolve.fallback: { "buffer": false }
Module not found: Error: Can't resolve 'fs' in '/Users/Filipp.Zhinkin/Development/kotlinx-io-release-tests/build/js/packages/kotlinx-io-release-tests-gradle-core-multiplatform-test/kotlin'
Module not found: Error: Can't resolve 'os' in '/Users/Filipp.Zhinkin/Development/kotlinx-io-release-tests/build/js/packages/kotlinx-io-release-tests-gradle-core-multiplatform-test/kotlin'

It's a blocker as it makes kotlinx-io-core useless in nodeJs-less environments.

[lppedd]

This really shows how much we need https://youtrack.jetbrains.com/issue/KT-47038.

This type of issue would be entirely avoidable.

[joffrey-bion]

Is there any workaround for this?

[joffrey-bion]

I just realized #256 was not released yet. I'm using 0.3.1 and I'm experiencing these errors already. So I'm not sure they are caused by the change you mention @fzhinkin

[fzhinkin]

@joffrey-bion I checked it with 0.3.1 and got error messages, but the code using the library worked fine (modulo UnsupportedOperationExcepion on an attempt to use a filesystem). Could you please elaborate on what kind of error you're facing?

[joffrey-bion]

For now I just noticed the webpack errors during the build (the ones mentioned in your original post). I haven't pin-pointed any runtime error, but since my build is not 100% working I am trying to get rid of every warning/error that looks fishy. If you say it's not cause for trouble, then I'm ok to wait until a new version of kotlinx-io fixes this 😉

[fzhinkin]

I'll investigate it further, but for now, it seems like warnings don't cause actual problems in runtime.