__dirname is not sufficient to derive the path to WASM file

[mPaella]

Problem

The compiled lib uses __dirname to resolve the path to cardano_serialization_lib_bg.wasm file, which does not always resolve correctly. Causing Error: ENOENT: no such file or directory, open '/project/sandbox/.next/server/app/foo/cardano_serialization_lib_bg.wasm'

Reproduction

https://codesandbox.io/p/sandbox/gifted-einstein-mo56ss?file=%2Fnext.config.js%3A19%2C7

• View the code sandbox
• See that both the app dir and pages dir are being used, and are calling the same function
• Browse to /. See that the page loads
• Browse to /foo. See that the page errors, due to incorrectly deriving the path to the WASM file

Fix?

As a hack to see if i could fix it, I tried editing the compiled files for @emurgo/cardano-serialization-lib under node_modules.

OLD - Not working - line ~14053 in the compiled code

const path = require('path').join(__dirname, 'cardano_serialization_lib_bg.wasm');

NEW - Working

const path = require('path').join(process.cwd(), "node_modules", "@emurgo", "cardano-serialization-lib-nodejs", 'cardano_serialization_lib_bg.wasm');

[mPaella]

This appears to be a problem with wasm-pack actually, ill bring it up over there

[lisicky]

Hi @mPaella ! Why did you choose the node csl version and not the browser version ?

[mPaella]

@lisicky I'm using @blockfrost/blockfrost-js which uses the node package.

Which i'm pretty confident is correct, as the code isn't being run in the browser.

If you are familiar with NextJs, in the reproduction you will see that the code is being run inside getServerSideProps (working correctly, pages directory, node env), as well as inside the async server component (NOT working, app directory, still node env)

[lisicky]

Thanks for clarification @mPaella ! It's better to create issue in Wasm-pack or next.js repo. Because it is issue of third-party tool

[lisicky]

Seems it was done by https://github.com/vercel/next.js/issues/49783