[Access] Fix race condition with block collection indexing

[peterargue]

Previously, the API required that the block/collection index exist if the tx/collection index did. These indices are store separately, so there is a race condition in which one may exists before the other.

This PR relaxes the check in the API to return a NotFound error in this case instead of throwing an exception.

Summary by CodeRabbit

• Bug Fixes

  • Transaction lookup now returns a clear "not found" response when the block for a submitted transaction is missing, instead of a generic error.

• Tests

  • Tests updated to assert both the explicit not-found outcome and the separate propagated error path for block lookup failures.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[coderabbitai]

📝 Walkthrough

Walkthrough

lookupSubmittedTransactionResult now treats a storage ErrNotFound from ByCollectionID as a NotFound status return instead of triggering an irrecoverable error; other errors remain wrapped and cause the irrecoverable path. Tests updated to cover both not-found and exception propagation paths.

Changes

Cohort / File(s)	Summary
Transaction error handling engine/access/rpc/backend/transactions/transactions.go, engine/access/rpc/backend/transactions/transactions_test.go	Handle ErrNotFound from ByCollectionID by returning a NotFound status; preserve irrecoverable behavior for other errors. Tests updated: one subtest verifies the not-found return, another verifies wrapped exception propagation.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 I dug through blocks with eager paws,
Found none and paused without a cause.
"Not found," I said, no panic spree—
Another bug fixed, hop—yippee! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main change: converting a race condition error path from an exception to a NotFound response when block/collection indices are out of sync.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch peter/allow-blockcollection-index-lag

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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