SyntaxError: Cannot use import statement outside a module

[mackwang112]

In my github actions, executing npx eslint --ext .js,.ts,.tsx,.jsx packages/ resulted in the following error:

npx eslint --ext .js,.ts,.tsx,.jsx packages/

Oops! Something went wrong! :(

ESLint: 7.32.0

/home/runner/work/mpx/mpx/node_modules/eslint-plugin-import/node_modules/async-function/require.mjs:1
(function (exports, require, module, __filename, __dirname) { import getAsyncFunction from './index.js';
                                                              ^^^^^^

SyntaxError: Cannot use import statement outside a module
    at new Script (node:vm:117:7)
    at NativeCompileCache._moduleCompile (/home/runner/work/mpx/mpx/node_modules/eslint/node_modules/v8-compile-cache/v8-compile-cache.js:240:18)
    at Module._compile (/home/runner/work/mpx/mpx/node_modules/eslint/node_modules/v8-compile-cache/v8-compile-cache.js:184:36)
    at Module._extensions..js (node:internal/modules/cjs/loader:1623:10)
    at Module.load (node:internal/modules/cjs/loader:1266:32)
    at Module._load (node:internal/modules/cjs/loader:1091:12)
    at Module.require (node:internal/modules/cjs/loader:1289:19)
    at require (/home/runner/work/mpx/mpx/node_modules/eslint/node_modules/v8-compile-cache/v8-compile-cache.js:159:20)
    at Object.<anonymous> (/home/runner/work/mpx/mpx/node_modules/eslint-plugin-import/node_modules/get-intrinsic/index.js:154:24)
    at Module._compile (/home/runner/work/mpx/mpx/node_modules/eslint/node_modules/v8-compile-cache/v8-compile-cache.js:192:30)

Yesterday, it was still working normally, and even after I re-ran npm i locally, I couldn't reproduce the issue; it only occurs in my github actions.

I'm not sure who is calling async-function/require.mjs; theoretically, perhaps it should use async-function/index.js, but I'm not familiar with it.

Maybe this has nothing to do with eslint-plugin-import, but I have no idea where to start troubleshooting.

[ljharb]

I recently published a different package that started using async-function. What node version are you using?

Do note that eslint 7 is many years EOL.

[mackwang112]

Thank you for the reminder.
My .github/workflows are specified to run based on ubuntu-latest, and when I add node -v, I get v20.19.5.

[rkawecki-cksource]

I've also observed this in the context of eslint. It seems like recent Node versions + old eslint somehow cannot require() an ESM file. It gets weirder, though - Node.js on its own seems okay with require()'ing this. It only fails when eslint requires async-function as a plugin's dependency.

• Node.js v20.18.2: runs eslint successfully (maybe it didn't read the mixed exports declaration from package.json, not sure)
• Node.js v22.19.0: produces the above error

But on 22.19.0, if I do:

node
> const asyncFunction = require('async-function')

it works. So Node on its own can deal with this package's use of ESM.

We've traced the issue to the package get-intrinsic@1.3.1.

If we override to always use get-intrinsic@1.3.0, eslint is back to normal. get-intrinsic@1.3.0 did not pull in async-function as a dependency.

[ljharb]

That's very strange - as far as i know eslint is just using require internally, on all versions.

[rkawecki-cksource]

As far as I can tell, in my case the require() is triggered from @rushstack/eslint-patch -> this requires eslint-plugin-import (at least according to stack traces).

@mackwang112 are you also using eslint-patch, or any other package that modifies how eslint does module resolution? Trying to find a common theme here.

[ljharb]

a name like "eslint-patch" suggests it's modifying the code of eslint on disk, which definitely voids any warranties anywhere.

[rkawecki-cksource]

I do think it monkey-patches require(). On the other hand, @rushstack/eslint-patch has 11.5M downloads weekly, so it might affect quite a few people.

AFAICT, the package was used to alter eslint's module loading logic so that plugins could be loaded from a shared config's node_modules. This way, when importing a shared eslint config, dependent packages didn't have to copy/paste all the devDependencies. In ESLint < 9, I believe this was the only way to "borrow" dependencies from an imported config package.

I guess the surprise here is that a patch-level version of get-intrinsic pulls in a new dependency not seen before, and this dependency unluckily relies on ESM/CJS compat that breaks when used with customized loaders (such as ESLint 7.x/8.x was often used with), some bundlers, etc.

Unfortunately, I cannot quite tell why it's trying to import the mjs version over the "legacy" version, which I understand was specifically prepared to avoid this problem.

[ljharb]

Can you file an issue on eslint-patch?