hi!
i got two backtraces from developer Herman BRULE (bt.txt and bt5.txt)

<https://sourceforge.net/p/httraqt/tickets/24/>

there is the problem in function sendc() of the htslib.c file

should be checked the pointer to r->soc:
if (r->soc != INVALID_SOCKET) {
   n = send(r->soc, s, ssz, 0);
}

thanks!