`data` is `null` on Functions when `useCallFunction` used

Classic way to call:

```
const functions = useContext(FirebaseFunctionsContext)!;
const rejectSingUpRequest = httpsCallable(functions, 'rejectSignUpRequest');
await rejectSignUpRequest({
  uid: userId,
});
```

...passes the data to backend. However, when `useCallFunction` is used, it is always `null` on backend.