atomWithImmer setting to undefined value

[Dad-rct]

Bug Description

When configuring an atomWithImmer that accepts undefined values, setting to undefined is a NOOP and doesn't work as expected.

import React from 'react';
import { atomWithImmer } from 'jotai-immer';
import { useAtom } from 'jotai';
const Test = atomWithImmer(undefined as number | undefined);
const TestWithNull = atomWithImmer(null as number | null);

export const App = () => {
  const name: string = 'Hello React Button';
  const [value, setValue] = useAtom(Test);
  const [valueNullable, setValueNullable] = useAtom(TestWithNull);
  const toggleState = React.useCallback(() => {
    setValue((value) => (value === undefined ? 1 : undefined));
  }, []);
  const toggleStateWithNull = React.useCallback(() => {
    setValueNullable((value) => (value === null ? 1 : null));
  }, []);
  return (
    <>
      <button onClick={toggleState}>
        Toggle State with undefined (defined=
        {value !== undefined ? 'yes' : 'no'})
      </button>
      <button onClick={toggleStateWithNull}>
        Toggle State with null (null={valueNullable !== null ? 'yes' : 'no'})
      </button>
    </>
  );
};

In the above example, toggling that state between undefined and number does not work as I would expect. You can set to a number, but not set back to undefined.

The nullable state works as expected.

Is this expected behaviour?

Reproduction Link

https://react-starter-typescript-61zk5bdn.stackblitz.io

[Dad-rct]

Realised after posting that this should perhaps be in jotai-immer. The issue is there where the calue isn't tested for undefined. With immer for undefined, produce has to return immer.nothing (https://immerjs.github.io/immer/return/#:~:text=Producing%20undefined%20using%20nothing%20%E2%80%8B&text=So%2C%20by%20default%2C%20Immer%20will,tried%20to%20modify%20the%20draft.&text=N.B.%20Note%20that%20this%20problem,t%20suffer%20from%20this%20issue.)

Tried to transfer discussion, but github won't allow as repo owned by different user.

I'll close and re-open there