Type error when overriding global fetcher function with null

Bug report

Description / Observed Behavior

When a global fetcher is configured using SWRConfig it can't be overridden locally by setting fetcher to null - a request still happens.

  // This results in a request to "/state"
  const first = useSWR("state", null);

If I set the fetcher to null in the config parameter it works, but that does not typecheck so a ts-ignore comment is needed.

  // This works but TS complains:
  // "Type 'null' is not assignable to type '((arg: "state") => any) | undefined'."
  const second = useSWR("state2", null, {
    fetcher: null,
  });

A workaround is to type the config as {}:

  useSWR<DataType, ErrorType, {}>("state2", null, {
    fetcher: null,
  });

Expected Behavior

No typescript errors displayed. In best case a null passed as fetcher should override global config.

Repro Steps / Code Example

https://codesandbox.io/p/sandbox/useswr-typing-bug-2d4prc?file=%2Fsrc%2FApp.tsx%3A10%2C32

Additional Context

SWR version 2.2.4