A shared component library shipped a real Spanish translation layer, and two hardcoded English aria-labels rode along for months anyway - because being 90% correct is better camouflage than being 0% correct.
A consent package that worked fine in production for months, until I turned on the one Astro feature that would have broken it from day one - and a stale closure that was never actually broken, just pointed at a ghost.
A README warning about a subtle failure mode is a confession that the code isn't tested against it yet.
Five pure-function modules, a timezone trap, and an import that worked in every consuming site because a bundler had been quietly covering for it.
A comment saying 'this is injectable so it can be tested outside a browser' sat there for months above a file with zero tests - and the shortest test in the file is the one that would have caught a real bug.
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