Initialise atom as null

[philipaarseth]

If you initialise an atom like this

export const objState = atom<Obj | null>(null)

It will think I want a read only atom and using it like a normal read/write atom will cause type issues as
const [obj, setObj] = useAtom(objState)
setObj will be of type never and calling it will make typescript complain never has no call signatures.

However if I use any other type than undefined or null like for instance atom<Obj | number>(0)
I can do if(typeof raid === "number") return just fine.

So how does one initialise an atom as null, then later check if that value is null and use that as a bail out mechanic?
Alternatively if there's another better approach here I'm all ears!

[dai-shi]

A quick question: Do you have "strict": true in tsconfig.json?

[philipaarseth]

No, "strict": false,

[dai-shi]

Can you try with true? It can't infer null properly with false.

Please see #550 (comment) for a workaround with "strict": false.

[philipaarseth]

Well it looks to be working, typescript isn't complaining about that part anymore.
However, I don't know if I have time to rewrite the project to be strict mode, also I'm not a huge fan of all the boilerplate.

Is there no other way?

[dai-shi]

To my knowledge, it's a limitation in TS, and I don't know any workaround other than that.
If your code allows it, you can use false instead of null. const objState = atom<Obj | false>(false)

[philipaarseth]

That's a shame, but alright I think that will have to do for now.
Thanks a ton!