keepPreviousData doesnt keep Error between refetch

[matzxrr]

Describe the bug

This bug is related to the keepPreviousData.

I have found that useQuery doesn't start tracking previous data until the query has returned with successful data from the queryFn.

In the event that queryFn encounters an Error on its first query, This error does not persist during a refetch.

If the useQuery call previously had a queryFn return with some type of valid data or the useQuery call was given some initialData, errors DO get persisted between fetches as you would expect.

Your minimal, reproducible example

https://codesandbox.io/s/rq-persist-error-first-rsrghk?file=/src/App.js:101-586

Steps to reproduce

1. Create a useQuery with keepPreviousData and a queryFn that errors on first request.
2. Inspect the error value between refetch, it will be null

export default function App() {
  const { error, isLoading } = useQuery({
    queryKey: ["badquery"],
    queryFn: () => axios.get("https://test.com/thisdoesntexist"),
    placeholderData: keepPreviousData,
    refetchInterval: 10_000,
    retry: false
  });

  // I would expect the previous error to stay when loading

  return (
    <div className="App">
      <h1>Hello CodeSandbox</h1>
      <p>{isLoading ? "is loading" : "loaded"}</p>
      <p>error: {error?.message}</p>
    </div>
  );
}

Expected behavior

As a user, I expect the error returned from useQuery to persist between refetches when the keepPreviousData option is set to true.

How often does this bug happen?

Every time

Screenshots or Videos

No response

Platform

OS: Windows 11
Chrome: Version 118.0.5993.118 (Official Build) (64-bit)

Tanstack Query adapter

react-query

TanStack Query version

v5.4.3

TypeScript version

No response

Additional context

No response

[TkDodo]

your example makes no sense. In order for keepPreviousData to do something, you need to be in a transition between query keys. With a static query key, it doesn't do anything.

also: data is always kept between refetches of the same queryKey. It's just that if you have no data, we go back to a hard loading state. That is per design. data is kept (stale while revalidate refers to showing stale data), errors are not.