@tus/s3-store: fix offset NaN when there are no parts

[Murderlon]

Closes #783

[changeset-bot]

🦋 Changeset detected

Latest commit: 2cffb87

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@tus/s3-store	Patch

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[coderabbitai]

Walkthrough

Adds a changeset for @tus/s3-store and updates calcOffsetFromParts in packages/s3-store/src/index.ts to avoid NaN offsets by summing S3 part sizes with a nullish coalescing fallback.

Changes

Cohort / File(s)	Summary
Release metadata ./.changeset/nasty-drinks-itch.md	Adds patch release note for @tus/s3-store: fix offset being NaN when no S3 parts are found.
S3 offset handling packages/s3-store/src/index.ts	calcOffsetFromParts now uses (b.Size ?? 0) in reduce; removes ts-expect-error. No exported API changes.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Assessment against linked issues

Objective	Addressed	Explanation
Fix NaN Upload-Offset in HEAD response when resuming uploads (#783)	✅

Assessment against linked issues: Out-of-scope changes

Code Change	Explanation
Add patch changeset entry (.changeset/nasty-drinks-itch.md)	Release metadata; not a functional change but acceptable accompanying change for the bug fix.

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[coderabbitai]

Actionable comments posted: 0

🧹 Nitpick comments (2)

.changeset/nasty-drinks-itch.md (1)

1-5: Changeset text and bump scope look correct (patch).

Message is clear and scoped to the S3 store. Minor nit: consider ending the sentence with a period for consistency with typical changeset prose.

Apply this tiny edit if you want:

-Fix offset being returned as `NaN` when there are no S3 parts found
+Fix offset being returned as `NaN` when there are no S3 parts found.

packages/s3-store/src/index.ts (1)

58-60: Solid fix: avoids NaN when S3 vendor returns undefined Part.Size.

Using b.Size ?? 0 with an initial accumulator of 0 closes the NaN hole and is safe for empty parts. You can simplify slightly by dropping the explicit length check.

Optionally, simplify and keep the guard explicit:

-function calcOffsetFromParts(parts?: Array<AWS.Part>) {
-  return parts && parts.length > 0 ? parts.reduce((a, b) => a + (b.Size ?? 0), 0) : 0
-}
+function calcOffsetFromParts(parts?: Array<AWS.Part>) {
+  const arr = parts ?? []
+  return arr.reduce((sum, p) => sum + (typeof p.Size === 'number' ? p.Size : 0), 0)
+}

If you’d like, I can add a regression test that stubs listParts to return a Part with Size: undefined and asserts getUpload(id).offset is numeric (0) rather than NaN.

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📥 Commits

Reviewing files that changed from the base of the PR and between 688a578 and 2cffb87.

📒 Files selected for processing (2)

• .changeset/nasty-drinks-itch.md (1 hunks)
• packages/s3-store/src/index.ts (1 hunks)