Unexpected undefined not assigned

🐛 Bug Report

When I assign "undefined" to the prop "foo" of draft, and the prototype of base has the prop "foo" which is "undefined",
the final return value is not assigned an "undefined" to the prop "foo".

To Reproduce

import { enablePatches, immerable, produceWithPatches } from "immer";

const proto = { [immerable]: true, name: undefined };
const foo = Object.create(proto);

console.log(`[hasOwnProp] foo:`, Object.prototype.hasOwnProperty.call(foo, "name"));

enablePatches();
const [foo_next, patches, _] = produceWithPatches(foo, (x) => {
  console.log(`[immer] produce foo_next from immer`);
  x.name = undefined;
});

console.log(`[immer] foo_next patches:`, patches);

console.log(`[hasOwnProp] foo:`, Object.prototype.hasOwnProperty.call(foo, "name"));
console.log(`[hasOwnProp] foo_next:`, Object.prototype.hasOwnProperty.call(foo_next, "name"));

foo.name = undefined;
console.log(`[vanilla] assign name manually`);
console.log(`[hasOwnProp] foo:`, Object.prototype.hasOwnProperty.call(foo, "name"));

Observed behavior

[hasOwnProp] foo: false
[immer] produce foo_next from immer
[immer] foo_next patches: []
[hasOwnProp] foo: false
[hasOwnProp] foo_next: false
[vanilla] assign name manually
[hasOwnProp] foo: true

Expected behavior

[hasOwnProp] foo: false
[immer] produce foo_next from immer
[immer] foo_next patches: [
  {
    op: "add",
    path: [ "name" ],
    value: undefined,
  }
]
[hasOwnProp] foo: false
[hasOwnProp] foo_next: true
[vanilla] assign name manually
[hasOwnProp] foo: true

Start by running the TypeScript reproduction with produceWithPatches and inspect the implementation paths it exercises for assignments inherited from a prototype. Compare the generated patches and own-property behavior with the expected output; done means assigning undefined creates an own property and an add patch without changing the original object.