Shared library
The data validation engine behind four products
git clone https://github.com/contentforge-press/datacheck-core2026-02-30 in a date column — parses fine, does not exist"$1,250.00" in a number column — becomes NaN, written as nullA-001 and A-1) — joins duplicate every rowN/A where you expected empty — passes a null check, poisons the join"A-1001 " trailing space — Merge returns zero rows, no error