fix(ENG-12540): prevent unhandled rejection cascade on ONNX load failure

[hiskudin]

Context

When the ONNX model fails to load (e.g. on Alpine where onnxruntime-node native binary can't load), void inFlight.finally(...) in _loadModel() creates an unhandled promise rejection. The NestJS global handler wraps and re-emits it, creating a recursive cascade ~130 levels deep on every request that triggers defender.

The growing error strings ("Unhandled rejection: [object Promise] reason: Error: Unhandled rejection: ..." × 130) consume memory continuously under production load, contributing to pod restarts.

Fix

Replace void inFlight.finally(...) with inFlight.finally(...).catch(() => {}).

The .catch(() => {}) silences the duplicate rejection from the .finally() chain. The actual error still propagates correctly through await inFlight → loadModel() catch → caller's try/catch.

One-line diff

- void inFlight.finally(() => _loadingPromises.delete(this.modelPath));
+ inFlight.finally(() => _loadingPromises.delete(this.modelPath)).catch(() => {});

🤖 Generated with Claude Code

---

Summary by cubic

Stop the unhandled rejection cascade when ONNX model loading fails, eliminating error storms and memory growth under load. Addresses ENG-12540 by catching the .finally() rejection while keeping the original error flow intact.

• Bug Fixes
  • Add .catch(() => {}) to the inFlight.finally(...) chain; the original error still propagates via await inFlight.
  • Add a test that asserts no unhandledRejection on model load failure and uses try/finally to reliably clean up the listener; document the catch inline.

^{Written for commit f11b785. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 1 file

_{Auto-approved: Isolated fix to prevent unhandled promise rejections and associated memory growth during ONNX load failures.}

[Copilot]

Pull request overview

This PR prevents an unhandled promise rejection cascade when the ONNX model load fails (e.g., native onnxruntime-node binary can’t load), by ensuring the promise created by the .finally() cleanup path is explicitly handled.

Changes:

• Replace void inFlight.finally(...) with inFlight.finally(...).catch(() => {}) to prevent an unhandled rejection from the .finally() chain on load failures.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[cubic-dev-ai]

1 issue found across 2 files (changes from recent commits).

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="specs/onnx-classifier.spec.ts">

<violation number="1" location="specs/onnx-classifier.spec.ts:87">
P3: Ensure the global unhandledRejection listener is always removed even when the test fails. Wrap the test body in a try/finally so the listener is cleaned up on all exits.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

0 issues found across 1 file (changes from recent commits).

_{Auto-approved: Fixes a critical production issue involving recursive error cascades and memory growth. The change is isolated, follows standard promise handling practices, and includes a regression test.}