Parcel.js: TypeError: Cannot read properties of undefined when all builds abort — results.pop() returns undefined

[tsushanth]

Bug

In packages/core/core/src/Parcel.js around line 358, the code does:

let result = results.filter(Boolean).pop();
result.type // TypeError if all builds were aborted

When all pending builds are aborted, results.filter(Boolean) produces an empty array and .pop() returns undefined. The subsequent property access (result.type or similar) throws:

TypeError: Cannot read properties of undefined (reading 'type')

Reproduction

Trigger a build abort (e.g. via AbortController) while multiple builds are queued or in-flight. The crash surfaces in the build result aggregation path.

Fix

Add a null guard before accessing result:

let result = results.filter(Boolean).pop();
if (!result) {
  return; // or handle as appropriate — all builds were aborted
}
// safe to use result.type here

Notes

This is distinct from the sort comparator and env invalidation hash issues in PR #10341 — this is a separate null-deref in the abort path.