Passing empty array for the ignored option causes webpack to ignore all files

[dextersealy]

If an empty array is passed to watchOptions.ignored then webpack ignores all files.

I believe the problem is this code that converts the ignored array into a function:

	if (Array.isArray(ignored)) {
		const regexp = new RegExp(ignored.map(i => stringToRegexp(i)).join("|"));
		return x => regexp.test(x.replace(/\\/g, "/"));

When ignored is an empty array, it returns a RegExp that matches all strings.