Did you load `tls` module before `http_async_client`? Also, this module has to be loaded before any other module using libcurl (see: https://www.kamailio.org/docs/modules/stable/modules/http_async_client.html#...)
For further troubleshooting, install the debug symbols packages for libcurl and libssl to get more details in the frames referencing them. Once installed, just grab again the `bt full` from all core files (no need to generate another crash).