union() in lib/utils/objectUtils.js uses a Set for large inputs (deduping both arrays) but a plain copy of the first array for small ones (deduping only the second). So duplicates in the first array survive only on the small-array path: union([1, 1, 2], [2, 3]) returns [1, 1, 2, 3] instead of [1, 2, 3].
PR: #2809
union()inlib/utils/objectUtils.jsuses aSetfor large inputs (deduping both arrays) but a plain copy of the first array for small ones (deduping only the second). So duplicates in the first array survive only on the small-array path:union([1, 1, 2], [2, 3])returns[1, 1, 2, 3]instead of[1, 2, 3].PR: #2809