[BUG REPORT] - ai.js crashes on malformed LLM cluster instead of retrying

[SegoCode]

Description

In code/js/ai.js, cluster validation assumes every LLM response item has a defined source field. When the model returns a malformed cluster (missing source or source: undefined), c.source.length throws a TypeError and kills the entire GitHub Actions workflow.

This should be treated as an invalid response and trigger the existing retry logic (lines 30-76), not abort execution.

Stack trace:

file:///home/runner/work/NewsBucket/NewsBucket/code/js/ai.js:72
    clusters.every((c) => c.count === c.source.length);
                                               ^

TypeError: Cannot read properties of undefined (reading 'length')
    at file:///home/runner/work/NewsBucket/NewsBucket/code/js/ai.js:72:47
    at Array.every (<anonymous>)
    at file:///home/runner/work/NewsBucket/NewsBucket/code/js/ai.js:72:13

Affected code (code/js/ai.js, lines 71-75):

const ok = clusters.length > 0 &&
    clusters.every((c) => c.count === c.source.length);
if (ok) break;
const why = clusters.length === 0 ? "empty" : "count mismatch";
if (!attempt) console.warn(`  ↻ retry 1/1 (${why})`);

Steps to reproduce

1. Run pnpm ai (or the Update news GitHub Actions workflow) against a feed with enough articles from the last 24 hours.
2. Wait for the LLM to return parseable JSON where at least one cluster is missing source or has a non-array source.
3. Observe that validation at line 72 throws TypeError before ok can evaluate to false.

Expected behavior

• A malformed cluster (source missing, null, or not an array) should fail validation safely.
• The pipeline should enter the retry path (↻ retry 1/1), same as for empty responses or count mismatches.
• Only after retries are exhausted should it throw an explicit error, never an unhandled TypeError during validation.

Actual behavior

• Array.every() calls c.source.length without checking that source exists.
• A single malformed cluster causes TypeError: Cannot read properties of undefined (reading 'length').
• The GitHub Actions job fails completely; no retry runs and remaining feeds are never processed.

OS version

Linux Other

Confirmation

• I performed a search of the issue tracker to avoid opening a duplicate issue
• I understand that not filling out this template correctly may lead to the issue being closed

[github-actions]

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[SegoCode]

Fixed in 5d4d21d validation now guards against missing/non-array source before reading .length