The heaps don't need to a 16Mi jobs capacity initially now that they can grow, so just arbitrarily pick 16 to start. Don't show a limit-max-jobs-ready value because it's meaningless now. The only limit is available memory. Also update comments to reflect reality.
One of the principles of the beanstalk protocol is that messages should be readable by both machines and humans. The old error messages didn't satisfy that property -- the numeric error codes and human-readable descriptions were distinct. So instead we'll deliver errors the same way as other messages: as a single descriptive upper-case word, possibly with underscores.