Camelizing nested properties with a null union breaks

[LordZardeck]

If you have a child prop that has a null union, Camelize stops trying to camelize that property. The following is a basic reproducable example:

import type { Camelize } from 'camelize-ts'
import camelize from 'camelize-ts'

type SnakeCasedChild = {
	foo_bar: string
}

type SnakeCasedParent = {
	child: SnakeCasedChild[] | null
}

type CamelCasedParent = Camelize<SnakeCasedParent>

const myObject: CamelCasedParent = camelize({
	child: [{ foo_bar: 'hello' }],
})

myObject.child?.map((child) => child.fooBar)

You'll notice that TypeScript complains that child.fooBar is not a valid property, but child.foo_bar is.

[LordZardeck]

I would start a PR that adds a failing test for this, but I this repository doesn't have type testing. That might be useful.

[LordZardeck]

Quick question, is there a reason not to just use type-fest's CamelCasedPropertiesDeep? seems redundant to have the same type. This library could just be the function to camelcase the properties at runtime. Since type-fest is a type-only library, it shouldn't have any extra build bloat.

[jonkoops]

I'd rather not add any dependencies to this project if we can avoid it. But we can certainly steal the implementation from type-fest if it works better (with proper attribution ofc).

[Balastrong]

I'm here with a model having a nullable item, asking to cover that case :D

I'm not a ts wizard so maybe I'm wrong, but I see that it works by adding | null next to {} | undefined here. Does it break anything else?

camelize-ts/src/index.ts

Lines 11 to 14 in 16759ac

	? U extends ({} | undefined)
	? Array<CamelizeObject<U>>
	: T[K]
	: T[K] extends ({} | undefined)