Im not sure if I understood the ecosystem correctly, but i want to point out that i also opened the same issue as discussion for @types/node. I hope thats alright.

As said in the comments on the discussion: I hope i raised this correctly, if not, please help me do it right 😄

Must say that this issue was a bit fussy, didn't exactly understood what you wanted us to do...
that's when i found AbortSignal.reason on MDN.

The signal.reason was added in node v17.2.0
so it's quite new...

Sorry for unclearity. I wasnt aware that its so new, because in the abort documentation they just say, that the parameter exists and I did not see that there is a specific page for AbortSignal.reason.

Yes it seems to be quite new, but it also seems quite handy to me. Thats why I opened the Issue to give the pointer. ^^

You can try and use the following snippet

try{
    fetch...
    } catch (error) {
if (abortController.signal.aborted) {
        return 'http request was timed out';
    }
}

You can try and use the following snippet

try{
    fetch...
    } catch (error) {
if (abortController.signal.aborted) {
        return 'http request was timed out';
    }
}

this approach is incredibly imprecise if the fetch could fail for multiple reasons, or if the AbortSignal could be triggered for different reasons (e.g. timeout vs process shutdown). Unless we can actually use the reason from the AbortSignal, we risk losing useful information and error context.

So I agree with OP that it would be very valuable to have node-fetch respect the reason field in the AbortSignal and change the error message thrown accordingly.

I believe the specifications says that, upon abort, the reason (when given) would be thrown instead of the default AbortError.

For me this is very invasive. It prevents detecting that an abort has occurred regardless of reason. A middle ground would be to set an error's cause with the reasen.

  try {
    const controller = new AbortController();
    const timeout = setTimeout(() => { controller.abort("took to long"); }, 1000 * 60);
    const response = await fetch("http://takes.very-long-time-to-resepond.com/api", {
      signal: contoller.signal,
    }).finally(() => clearTimeout(timeout));
    /* use response */
  } catch (error) {
    if (error instanceof AbortError) {
      console.log("fetch aborted");
      if (error.cause === "took to long") {
        console.log("because it took so long");
      } else {
        throw new Error("Unknown abortion", { cause: error });
      }
    } else {
      throw new Error("Unknown error", { cause: error });
    }
  }

Alternatively, the AbortError could carry a reference of the AbortSignal that triggered the abortion.

But never throw the reason.

Node's implementation of fetch does throw the given reason, validating that it is an object otherwise a TypeError is thrown.