Hello there,
Kamailio is terminating with signal 11 and is generating a coredump file. 
I opened the core file generated by it and it seems to be related to the module http_async_client.

In the following link you can find the output of core dump backtrace full: https://pastebin.com/rapPZy9N

Below is the http_async_client config that I have:

modparam("http_async_client", "workers", 2)
modparam("http_async_client", "connection_timeout", 500)
modparam("http_async_client", "hash_size", 2048)
modparam("http_async_client", "curl_verbose", 0)
modparam("http_async_client", "memory_manager", "shm")

If the information provided is not enough to troubleshoot this issue let me know.

Many thanks 

Best Regards
-- 
Cumprimentos
José Seabra