Unable to use snapshot.matches because partialStatevalue: never.

[pauldesmondparker]

I have not been able to produce a minimal reproducible repo, which is why I'm asking in the discussion in case someone else has seen this before and can point me in the right direction.

This react app https://stackblitz.com/edit/github-xgpyfx?file=src%2FfeedbackMachine.ts works and mirrors the general structure of my machine, i.e. there are parallel states at the root level.

This example is using createActor, actor.start(), useSelector and snapshot.matches.
Dependencies match on local:

    "@xstate/react": "5.0.0",
    "xstate": "5.19.0",
    "react": "18.3.1",
    "react-dom": "18.3.1",
    "typescript": "5.7.2",

In my local nextjs app when I try to use snapshot.matches I am getting this partialStateValue: never indicating that there are no states???:

(property) MachineSnapshotBase<TContext extends MachineContext, TEvent extends EventObject, TChildren extends Record<string, AnyActorRef | undefined>, TStateValue extends StateValue, TTag extends string, TOutput, TMeta, TStateSchema extends StateSchema = StateSchema>.matches: (partialStateValue: never) => boolean

There are no typescript errors on the machine definition.

Has anyone seen this or known what painful mistake I might be making?

[Andarist]

It's hard to tell if you don't share a repro case. To help out we need to see what exact code you have written

[pauldesmondparker]

The issue was that I was using:

// @ts-expect-error exactOptionalPropertyTypes

To mask this bug #4613, which in turn masked another error which caused it not to generate the signature. I temporarily turned off exactOptionalPropertyTypes for the repo and found the error.