Two windows where settle() could read a live waiter count, mark the
task reported (suppressing the completion notice), and then watch that
waiter reject with 'wait aborted' delivering nothing — leaving the
owning session with no terminal notification at all:
- abort and settlement in the same tick, settle continuation ordered
first: the waiter now un-counts itself SYNCHRONOUSLY inside onAbort
(the finally decrement alone lands a microtask too late), so the
settle path sees no live waiter and the notice fires;
- abort landing after settlement but before the wait's resolve
microtask: the wait now resolves and DELIVERS the terminal snapshot
it owes instead of rejecting (settlement suppressed the notice on
this waiter's behalf).
Both windows pinned by deterministic tests that fail on the previous
implementation; wait()'s abort contract updated in JSDoc/README/RFC.