🧪 add missing error test for untrack()

[undivisible]

🎯 What: The testing gap where untrack's finally block wasn't verified on thrown errors.
📊 Coverage: Now tests the exact tracking state before, during, and after an intentionally thrown error using reactive primitives, guaranteeing currentTracker restoration is bulletproof.
✨ Result: Better confidence in untrack error handling with no risk of state leakages.

---

PR created automatically by Jules for task 16104283232866966348 started by @undivisible

---

Note

Low Risk
Test-only change with no production code modifications.

Overview
Adds a regression test under the untrack suite that throws inside an untrack callback and asserts the outer reactive tracker is restored (mirroring the existing collectDeps error test).

The scenario uses a memo that tracks s1 and s3, reads s2 only inside untrack, then throws; afterward updates to s2 must not re-run the memo, while s1 and s3 still invalidate it.

^{Reviewed by Cursor Bugbot for commit 08dc949. Configure here.}

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.

[cursor]

Bugbot couldn't run - usage limit reached

Bugbot is counted against Cursor usage for this user or team, and this run hit a usage or spend limit.

A user or team admin can review and increase usage limits in the Cursor dashboard.

(requestId: serverGenReqId_c2b6abfd-33a9-4f28-8196-496637b14502)