fix(mock): guard aborted requests in async reply callback rejection

[pacocartones]

Problem

In lib/mock/mock-utils.js, sendReply() handles an async reply options callback (the .reply(() => ...) / response.callback path from #5534). Its resolve arm goes through handleReply() (guarded by if (aborted) return), but the reject arm called handler.onResponseError(null, err) with no abort guard.

When a request with a body is aborted while that options-callback promise is still pending, controller.abort() already settles the request via onResponseError (first terminal). The callback promise then rejects and calls onResponseError again → a double-settle of an already-aborted request.

This is distinct from #5762: that one guards the data/body function promise in handleReply(); this guards the reply options callback promise in sendReply() — different function, different call site, different feature.

Fix

Guard the reject arm with if (aborted) return, mirroring the guard handleReply() already applies.

Test

test/mock-delayed-abort.js: a CountingHandler counts onResponseError; a POST with a body and an options callback that rejects at 50ms, aborted at 10ms, asserts onResponseError fires exactly once.

• Before: 2 !== 1 (double-settle).
• After: exactly once.

node --test test/mock-delayed-abort.js (4 pass), whole mock suite via borp (340 pass), npm run lint — all green.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.52%. Comparing base (17117f6) to head (60b61f6).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5764      +/-   ##
==========================================
+ Coverage   93.50%   93.52%   +0.01%     
==========================================
  Files         110      110              
  Lines       39072    39080       +8     
==========================================
+ Hits        36534    36549      +15     
+ Misses       2538     2531       -7     

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[pacocartones]

The only non-green checks are two cancelled CI jobs (Node.js 24 Ubuntu coverage and Node.js 22 Ubuntu). I tried the Actions rerun endpoint, but contributors receive HTTP 403. Could a maintainer rerun the cancelled jobs when convenient?