The per-IP ingress limiter is an async Express middleware, and Express 4 does
not catch a rejected promise from a handler. If the rate-limiter backend is
unreachable, ipLimiter.limit() rejects, next() is never called, and the request
hangs until the client times out. Wrap the check in try/catch and let the
request through on a limiter error (the per-endpoint limiter is the real
protection), matching the OTLP ingress limiter.
Eric Allam
7b8ad85937