How to use immer to value to nested fields which have optional parents, in typescript?

Question

When I have an object which has nested optional fields, like:

type FormState = {
  aaa?: {
    bbb?: {
      ccc?: number
    }
  }
}

When I want to set value to aaa.bbb.ccc in typescript, I have to:

import produce from "immer";

const formState: FormState = {}

const target = produce(formState, draft => {
  draft.aaa = draft.aaa ?? {}
  draft.aaa.bbb = draft.aaa.bbb ?? {}
  draft.aaa.bbb.ccc = 1;
})

Is there any way to make it simpler?

The optional chaining syntax isn't work here:

draft?.aaa?.bbb?.ccc = 1;  // compilation error

A small demo: https://github.com/freewind-demos/typescript-immer-set-value-to-nested-optional-fields-demo