Avoid add type undefined on data

[Alecell]

I'm currently working on a typescript project that gives me this annoying error:

No overload matches this call.
  Overload 1 of 2, '(o: {}): string[]', gave the following error.
    Argument of type 'Data<Session & SessionCollection> | {} | undefined' is not assignable to parameter of type '{}'.
      Type 'undefined' is not assignable to type '{}'.
  Overload 2 of 2, '(o: object): string[]', gave the following error.
    Argument of type 'Data<Session & SessionCollection> | {} | undefined' is not assignable to parameter of type 'object'.
      Type 'undefined' is not assignable to type 'object'.ts(2769)

I get that this are happening because of that undefined:

Data<Session & SessionCollection> | {} | undefined

The point is that my implementation of the service never will be undefined, what makes me think that this undefined came from inside of the typing of the react-query. It seems to me that the lib tries to handle the error data of our services for us, but imo that's about to us to type and define. On my case for instance, I have a method that return a key-value object or an empty object:

static list(
    params: UrlParams,
  ) {
    return campaignRequest(params)
      .collection(EFirestoreCollections.SESSIONS)
      .get()
      .then((res) => res.docs.reduce((session, obj) => {
        const temp = session;

        temp[obj.id] = {
          id: obj.id,
          name: obj.data().name,
        };

        return temp;
      }, {} as ListSessionsState['data']))
      .catch((error) => {
        console.error('Error writing document: ', error);
        return {};
      });
  }

If we get the inferred type by the method, without react-query:

Promise<Data<Session & SessionCollection> | {}> 

But for some reason react-query infers that it could be undefined which isn't true. By far, react-query has a really good type inference on the lib so maybe is a good idea to let us to define all the types on the service is the best approach.

But perhaps I'm missing something or doing something wrong, in my situation is there a real case that this undefined will truly appears?

[TkDodo]

the data property returned by useQuery can be undefined for various reasons:

• if you disable the query via enabled: false, it will be in idle state and data will be undefined
• if you are running a query for the first time, you have no data yet and the query will be in loading state with undefined data
• if an error occurs (a rejected Promise, because e.g. your internet connection terminates mid-request), the query will transition to error state and if you've never gotten data from the backend, data will be undefined.