isPlainObject function is wrong

[zozzz]

Hi, this function is wrong:

webpack-merge/src/join-arrays.ts

Lines 63 to 65 in 2e8780e

	function isPlainObject(a) {
	return typeof a === "object";
	}

because returns true when a is null so currently, isPlainObject(null) === true. Why not use is-plain-object package instead?

[bebraw]

I went with the minimal amount of external dependencies.

Can you send me a test case where the current check is problematic? Simple configurations to merge would do.

[zozzz]

const { merge } = require("webpack-merge")

const a = {
    devServer: { base: true }
}

const b = {
    devServer: null
}

console.log(merge(a, b))

expected result: { devServer: null }

[bebraw]

Fixed in 5.1.2. Thanks!