fix(ci): tolerate null PR fields and honour existing area/* in pr-labeler

[Aleksei Sviridkin (lexfrei)]

Follow-up to #16. Addresses two correctness bugs in computeLabels (.github/scripts/pr-labeler.js) caught in review.

The bugs

1. Null inputs crash body.match(). computeLabels destructured title / body / existingLabels with = '' defaults. Destructuring defaults only fire on undefined. GitHub PR payloads carry an explicit null for an empty body (and, less commonly, for missing fields), which would slip past the default and crash on the first .match() or Set iteration. Switched to explicit rawTitle || '' / rawBody || '' / new Set(rawExisting || []) so null on any input is treated as the empty value.

2. hasArea ignored existing area/ labels.* A maintainer-added area/forms followed by a scopeless retitle (e.g. chore: housekeeping) would re-add area/uncategorized on top of the real area. The next labeler run would clean it up, but the PR carried both labels until then. Fixed hasArea to also consider already-attached real area/*, with area/uncategorized itself excluded so a scopeless retitle of an only-uncategorized PR still routes through the fallback path.

Tests

Five new cases in pr-labeler.test.js, all pinning behaviour that fails without the corresponding fix:

• null body does not throw
• null title is treated as empty
• null existingLabels does not throw
• retitle to scopeless when maintainer-added area/* exists: no area/uncategorized — stale fallback gets removed
• existing only has area/uncategorized: scopeless title keeps area/uncategorized (no churn) — fallback path still taken, no flapping

26 tests pass (node --test .github/scripts/*.test.js).

Note

pr-labeler.yaml already coerces pr.title || '', pr.body || '', (pr.labels || []) at the caller, so fix #1 is defense-in-depth at the function boundary. Worth keeping — the function contract should not rely on every caller doing the coercion.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: fb6b12e7-9ec8-4b1b-b31d-566368ca813d

📥 Commits

Reviewing files that changed from the base of the PR and between 92ff040 and 65fe842.

📒 Files selected for processing (2)

• .github/scripts/pr-labeler.js
• .github/scripts/pr-labeler.test.js

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/pr-labeler-null-safe

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[gemini-code-assist]

Code Review

This pull request improves the robustness of the PR labeler script by adding null-safety checks to the destructured parameters of computeLabels, preventing runtime errors when GitHub payloads contain explicit null values. Additionally, it updates the fallback logic to honor existing, maintainer-added area/* labels (excluding area/uncategorized) so that the fallback label is not redundantly applied. Comprehensive unit tests have been added to verify these changes. No review comments were provided.

[Maxim Kitsunoff (kitsunoff)]

LGTM. Null-safety at the function boundary is the right call (defence in depth even with caller-side coercion), and excluding area/uncategorized from the hasArea check avoids freezing the fallback in place.