X_FINITE_BOUND_UNCHECKED

a numeric option is defaulted with ?? and never checked for finiteness

?? guards nullish, and NaN is not nullish — so Number(process.env.X) on an unset variable, a parseInt of a typo and an untyped config value all walk past the default and land on the bound intact. Math.max/Math.min/Math.floor are not validators either: all three propagate NaN, and this repo relied on all three as guards. Four measured outcomes — a comparison that reads false forever (a dead worker's job never reclaimable, an AcceptBudget admitting the whole herd), an Array.from({ length: NaN }) or slice(0, NaN) that is [] (zero workers, reported as success), a setTimeout(fn, NaN) that is setTimeout(fn, 0) (a poll becomes a spin), and a loop that never terminates, synchronously, past every AbortSignal. Matched on the missing CHECK, never on the option's name

assert(Number.isFinite(value), '…', '…') where the option is read — packages/jobs/src/limits.ts's concurrencyLimiter is the form. bun run finite-bounds --explain --json lists every site