Receptor exits with zero when unable to listen #180

Try running the following commands twice, concurrently:

poetry run receptor --data-dir="$(mktemp --directory)" node

One process will bind to 0.0.0.0:8888, and the other will fail to bind and bail. The process that bails should, intuitively, exit with a non-zero status code. However, it exits with a zero status code. This seems wrong.