io/StatAt: don't use OpenPath() because it throws
io/StatAt: don't use OpenPath() because it throws

StatAt() doesn't throw, but returns `false` on error.

CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy