Yes, tls module loaded first. I created a minimal config file that reproduces the problem. The crash is because of this line: modparam("http_async_client", "workers", 4) comment out this line makes the crash disappear.
#!KAMAILIO
####### Global Parameters #########
/* LOG Levels: 3=DBG, 2=INFO, 1=NOTICE, 0=WARN, -1=ERR, ... */ debug=2 log_stderror=no memdbg=5 memlog=5
log_facility=LOG_LOCAL0 log_prefix="{$mt $hdr(CSeq) $ci} "
children=8 tcp_children=16 auto_aliases=no alias="example.com"
listen=udp:eth0 server_signature=no tcp_connection_lifetime=3605 tcp_max_connections=40960 tcp_accept_no_cl=yes enable_tls=yes listen=tls:eth0 tls_max_connections=40000 enable_sctp=no
####### Modules Section ########
loadmodule "kex.so" loadmodule "corex.so" loadmodule "tm.so" loadmodule "tmx.so" loadmodule "sl.so" loadmodule "rr.so" loadmodule "pv.so" loadmodule "tls.so" loadmodule "http_async_client.so"
# ----------------- setting module-specific parameters ---------------
# ----- tls params ----- modparam("tls", "config", "/etc/kamailio/tls.cfg")
# ----- http client ---- modparam("http_async_client", "workers", 4)
####### Routing Logic ########
request_route { exit; }