setup-node/node_modules/strip-bom/index.js

'use strict';
module.exports = x => {
	if (typeof x !== 'string') {
		throw new TypeError('Expected a string, got ' + typeof x);
	}

	// Catches EFBBBF (UTF-8 BOM) because the buffer-to-string
	// conversion translates it to FEFF (UTF-16 BOM)
	if (x.charCodeAt(0) === 0xFEFF) {
		return x.slice(1);
	}

	return x;
};