mod_firewall: Initialize compiled chunk just once for all handlers This should fix a case where some stateful dependencies (such as throttles) produce separate instances for every call to new_handler(), leading to surprising behaviour (e.g. rules executed via JUMP CHAIN vs ::deliver would have separate rate limits). This also adds better error handling in case the compiled code fails to run for some reason.

This module discards typing notifications sent to a bare host JID,
preventing error replies to be sent. These errors are harmless but can
be annoying sometimes if your client shows them prominently.