connectSocket captured only resolve from Promise.withResolvers and its
error handler merely errored the stream, so a Bun.connect failure
(ECONNREFUSED/ENOENT/EACCES on a stat-ready-but-dead socket) never
settled the promise. The unbounded await in #spawnSocketUnix then hung
the launch forever, and the surrounding kill/reap guard could not fire.
Capture reject, track an opened flag, reject on error/close-before-open
and on the Bun.connect promise rejection, and bound the connect with a
timeout matching the launch deadline (cleared on settle). Thread
timeoutMs from #spawnSocketUnix. Export connectSocket for a deterministic
reject-path test.
Fixes#4087
roboomp
3b194a3e37