getFetcherType doesn't return done after submit

[Xelson]

Describe the bug

If a fetcher submitting to an action handler that returns null then getFetcherType returns idle after submission instead of done.
This happens because the initial fetcher.data value is undefined, but in the code if (fetcher.state === "idle" && fetcher.data != null) return "done", fetcher.data is being checked for null

Your Example Website or App

https://stackblitz.com/edit/remix-run-remix-hpas2u?file=app%2Froutes%2F_index.tsx

Steps to Reproduce the Bug or Issue

1. Go to stackblitz page with reproduce example;
2. Press every button on the page. The alert about submission will appear only after pressing the second one.

Expected behavior

If fetcher is triggering action which returning null value, getFetcherType should be done, not idle

Screenshots or Videos

No response

Platform

• OS: Windows 10
• Browser: Brave

Additional context

No response