TypeError: Cannot destructure property 'socket' of 'parser.deref(...)' as it is undefined.

[vbfox]

Bug Description

While running an internal test-suite this error is triggered inside the unidici version embedded in NodeJS:

Uncaught TypeError: Cannot destructure property 'socket' of 'parser.deref(...)' as it is undefined.
 at Timeout.onParserTimeout [as _onTimeout] (node:internal/deps/undici/undici:7501:15)
 at listOnTimeout (node:internal/timers:607:11)
 at process.processTimers (node:internal/timers:541:7)

Reproducible By

I could not reproduce out of essentially running our full test suite, it looks like a very timing dependent issue. Especially as it only occurs on developer laptops (macs) where the CI (linux) isn't affected.

We also use sinon fake timers, so the situation that trigger this bug might be impossible when the time flow normally and can't be "frozen".

Expected Behavior

No crash inside undici.

Environment

Node JS 24.13.0, macOS 26.2

[vbfox]

After tests I confirm that it is due to clearTimeout not being called with onParserTimeout when undici expect it due to timer mocking.

I still think it's better to fix the access to an undefined object, but the conditions for the code to reach this state are very special and shouldn't happen in any real environment.