npm script fails with "SyntaxError: Cannot use import statement outside a module"

[uluhonolulu]

Prerequisites

• I have searched for duplicate or closed issues
• I have validated any HTML to avoid common problems
• I have read the contributing guidelines

Describe the issue

I'm trying to run npm run css-prefix-main from the root of the cloned repository (tried both the main branch and the v4.3.1 tag). I'm consistently getting "SyntaxError: Cannot use import statement outside a module".

Here's the full output:

$ npm run css-prefix-main 

> bootstrap@5.1.3 css-prefix-main C:\Emr\Tools\bootstrap
> postcss --config build/postcss.config.js --replace "dist/css/*.css" "!dist/css/*.rtl*.css" "!dist/css/*.min.css"

C:\Emr\Tools\bootstrap\node_modules\postcss-cli\index.js:3
import fs from 'fs-extra'
^^^^^^

SyntaxError: Cannot use import statement outside a module
    at Module._compile (internal/modules/cjs/loader.js:895:18)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:995:10)
    at Module.load (internal/modules/cjs/loader.js:815:32)
    at Function.Module._load (internal/modules/cjs/loader.js:727:14)
    at Function.Module.runMain (internal/modules/cjs/loader.js:1047:10)
    at internal/main/run_main_module.js:17:11
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! bootstrap@5.1.3 css-prefix-main: `postcss --config build/postcss.config.js --replace "dist/css/*.css" "!dist/css/*.rtl*.css" "!dist/css/*.min.css"`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the bootstrap@5.1.3 css-prefix-main script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\uluho\AppData\Roaming\npm-cache\_logs\2021-12-29T08_53_13_023Z-debug.log

Reduced test cases

No test case, just clone the repo and run the command.

What operating system(s) are you seeing the problem on?

Windows

What browser(s) are you seeing the problem on?

No response

What version of Bootstrap are you using?

v5.1.3

[ffoodd]

Please check your node & npm version, this doesn't seem like something on our end since our CI builds.

FYI we're currently using node 16, if I recall correctly.

[uluhonolulu]

Weird, I have node v12, it's supposed to support ES6 modules. Anyway, after digging a bit more, I believe it's actually a postcss issue, closing.

[movy]

might help: postcss/postcss-cli#387