fix(ratelimiter): log metrics server failure instead of swallowing it

[mesutoezdil]

setupMetrics swallowed the ListenAndServe error in an empty branch, so a
failed Prometheus bind left the service running with no metrics and no log
line. Now logs at error level, matching setupPprof and setupOlricStats.

Issues

Closes #540

Summary by CodeRabbit

• Bug Fixes
  • Added error logging when the rate-limiter metrics service fails to start, improving visibility into service startup issues.

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📥 Commits

Reviewing files that changed from the base of the PR and between 13c2ab5 and b18291b.

📒 Files selected for processing (1)

• src/invocation-plane-services/ratelimiter/cmd/main.go

🚧 Files skipped from review as they are similar to previous changes (1)

• src/invocation-plane-services/ratelimiter/cmd/main.go

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📝 Walkthrough

Walkthrough

The rate-limiter metrics HTTP listener now logs errors returned by ListenAndServe, including failures to start the /metrics server.

Changes

Rate-limiter metrics

Layer / File(s)	Summary
Log metrics listener failures src/invocation-plane-services/ratelimiter/cmd/main.go	Records ListenAndServe failures with an error-level zap log.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Mergeability Score: ⚪ Minimal · up to b1829

This localized change makes metrics server failures visible at error level without changing service behavior; no actionable merge-blocking risk remains beyond normal checks and review.

Suggested reviewers: balajinvda

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title uses valid Conventional Commits syntax and accurately describes the ratelimiter bug fix.
Linked Issues check	✅ Passed	The change logs the metrics listener failure and addresses the empty error branch described in [#540].
Out of Scope Changes check	✅ Passed	The one-line change is limited to logging metrics server failures and has no unrelated modifications.

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• Create PR with unit tests

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