If it helps someone, here is a minimal config that exposes the issue at startup:
``` #!KAMAILIO
debug=3 log_stderror=yes
children=2
listen=udp:127.0.0.1 listen=tcp:127.0.0.1
loadmodule "tm.so" loadmodule "pv.so" loadmodule "http_async_client.so"
request_route { return; } ```