require(...) is not a function

[Scrum]

I've faced with a similar in AlexWayfer/flame-cli#57 (I'm trying to replace SCSS with PostCSS completely, so it's not quite this PR, but based on it).

> postcss assets/styles/ -d public/styles/ --base assets/styles/ --ext=css

TypeError: require(...) is not a function
    at Object.<anonymous> (/home/alex/Projects/ruby/test/foo_bar/postcss.config.js:3:40)
    at Module._compile (node:internal/modules/cjs/loader:1102:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1131:10)
    at Module.load (node:internal/modules/cjs/loader:967:32)
    at Function.Module._load (node:internal/modules/cjs/loader:807:14)
    at Module.require (node:internal/modules/cjs/loader:991:19)
    at module.exports (/home/alex/Projects/ruby/test/foo_bar/node_modules/.pnpm/import-fresh@3.2.2/node_modules/import-fresh/index.js:32:59)
    at loadJs (/home/alex/Projects/ruby/test/foo_bar/node_modules/.pnpm/cosmiconfig@7.0.0/node_modules/cosmiconfig/dist/loaders.js:16:18)
    at Explorer.loadFileContent (/home/alex/Projects/ruby/test/foo_bar/node_modules/.pnpm/cosmiconfig@7.0.0/node_modules/cosmiconfig/dist/Explorer.js:84:32)
    at Explorer.createCosmiconfigResult (/home/alex/Projects/ruby/test/foo_bar/node_modules/.pnpm/cosmiconfig@7.0.0/node_modules/cosmiconfig/dist/Explorer.js:89:36)

My configuration:

// postcss.config.js

module.exports = {
	plugins: [
		// there can be more, but it's reproducible only with this package
		require('postcss-at-rules-variables')({ atRules: ['media'] })
	]
}

package.json:

	"dependencies": {
		"@babel/core": "*",
		"@babel/plugin-transform-object-assign": "*",
		"@babel/preset-env": "*",
		"@rollup/plugin-babel": "*",
		"@rollup/plugin-commonjs": "*",
		"@rollup/plugin-json": "*",
		"@rollup/plugin-node-resolve": "*",
		"autoprefixer": "*",
		"postcss-at-rules-variables": "*",
		"postcss-cli": "*",
		"postcss-flexbugs-fixes": "*",
		"postcss-mixins": "*",
		"postcss-nested": "*",
		"promise-polyfill": "*",
		"rollup": "*",
		"sass": "*",
		"simplify-js": "*",
		"whatwg-fetch": "*"
	},
	...
	"scripts": {
		"build:styles": "postcss assets/styles/ -d public/styles/ --base assets/styles/ --ext=css",
		...
	}

With version lock like this:

"postcss-at-rules-variables": "^0.1.0",

there is no such error.

Originally posted by @AlexWayfer in #204 (comment)