fix(host): Granular error handling in server loop

[clabby]

Overview

Currently, the host does not granularly handle errors in the hint router or preimage server loop. This is an issue, since certain errors should cause a throw, while others (like the file descriptor being closed) should exit gracefully.

Change the loops' error handling to handle File Descriptors being closed and/or EOF being reached, and exit gracefully, while throwing on any other error kinds.

Reference: https://github.com/ethereum-optimism/optimism/blob/develop/op-program/host/host.go#L241