Can't yarn build on M$ Win* Git Bash

[VincentTam]

The system complains "'BABEL_ENV' is not recognized as an internal or external command".

showdown-katex/package-scripts.js

Lines 17 to 31 in eaf3647

	build: {
	default: series(
	'nps clean',
	crossEnv(
	`NODE_ENV=production ${concurrent.nps(
	'build.umd',
	'build.cjs',
	'build.min',
	)}`,
	),
	),
	umd: 'BABEL_ENV=build rollup -c',
	min: 'BABEL_ENV=build rollup -c --environment MIN',
	cjs: 'BABEL_ENV=build rollup -c --environment TARGET:cjs',
	},

This is similar magento/pwa-studio#898: the use of BABEL_ENV=build at the beginning of a command is fine on Unix, but not on M$ Win*. The following screenshot shows that the command works on WSL (Windows Subsystem for Linux)

The linked PR's author suggests adding the node.js package cross-env in the dependencies. Lacking knowledge in node.js, I'll leave that for others to think about.