`ERR_PACKAGE_PATH_NOT_EXPORTED` with conditional ESM export from module about postcss

[ai]

Sorry, I can’t help with debugging Node.js. This is a question for Stack Overflow or Node.js community.

[silverwind]

The question is: does postcss load it's plugins through regular import or some other nonstandard module loader? If the later, it is very much related to postcss. Have you even looked at the repro?

[ai]

Mostly default require(), but there are a hack for TS https://github.com/postcss/postcss-load-config/blob/main/src/req.js

[silverwind]

This here confirms that node can load both variants fine, but postcss cannot:

$ echo '{"type": "module", "exports": {".": "./index.js"}}' > config/package.json && node -e 'import("config").then(console.log)'
[Module: null prototype] { config: {} }
$ echo '{"type": "module", "exports": {".": {"import": "./index.js"}}}' > config/package.json && node -e 'import("config").then(console.log)'
[Module: null prototype] { config: {} }

[silverwind]

I think the root problem is that you are using createRequire which will give you the legacy CJS loader instead of the ESM loader, and the CJS loader will not use the import entry point but the require one which does not. So in essense, postcss plugins can not be pure ESM.

[ai]

Got it, what eactly you asked.

Yes, we do not suppor ESM plugins yet. You may try to create a PR to postcss-load-config if you have a good plan.

But I don’t think that it will be easy (this is why don’t have it).

[silverwind]

Actually the bug is in the tailwindcss plugin because even after importing the plugin directly in the postcss config, the error persists. The error stack trace has no postcss in it, so I'm certain this is not a postcss bug.

Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: No "exports" main defined in node_modules/config/package.json
    at new NodeError (node:internal/errors:405:5)
    at exportsNotFound (node:internal/modules/esm/resolve:261:10)
    at packageExportsResolve (node:internal/modules/esm/resolve:535:13)
    at resolveExports (node:internal/modules/cjs/loader:547:36)
    at Module._findPath (node:internal/modules/cjs/loader:621:31)
    at Module._resolveFilename (node:internal/modules/cjs/loader:1034:27)
    at Function.resolve (node:internal/modules/helpers:136:19)
    at _resolve (node_modules/jiti/dist/jiti.js:1:250334)
    at jiti (node_modules/jiti/dist/jiti.js:1:252917)
    at tailwind.config.js:1:329 {
  code: 'ERR_PACKAGE_PATH_NOT_EXPORTED'