#0  0x00007ffe3e93f849 in raise () from /lib64/libc.so.6
#1  0x00007ffe3e940cd8 in abort () from /lib64/libc.so.6
#2  0x00007ffe3e938616 in __assert_fail_base () from /lib64/libc.so.6
#3  0x00007ffe3e9386c2 in __assert_fail () from /lib64/libc.so.6
#4  0x0000000000512abe in FlushChannel (interp=0x0, chanPtr=0x19a84d0, 
    calledFromAsyncFlush=1) at /home/sbron/src/tcl8.6.3/generic/tclIO.c:2816
#5  0x0000000000519987 in Tcl_NotifyChannel (channel=0x19a84d0, mask=4)
    at /home/sbron/src/tcl8.6.3/generic/tclIO.c:8089
#6  0x000000000058767a in WrapNotify (clientData=0x19b2430, mask=4)
    at /home/sbron/src/tcl8.6.3/unix/tclUnixSock.c:957
#7  0x000000000058aa37 in FileHandlerEventProc (evPtr=0x19a3b10, flags=-3)
    at /home/sbron/src/tcl8.6.3/unix/tclUnixNotfy.c:765
#8  0x000000000053ac1a in Tcl_ServiceEvent (flags=-3)
    at /home/sbron/src/tcl8.6.3/generic/tclNotify.c:670
#9  0x000000000053b056 in Tcl_DoOneEvent (flags=-3)
    at /home/sbron/src/tcl8.6.3/generic/tclNotify.c:967
#10 0x00000000004e4f88 in Tcl_VwaitObjCmd (clientData=0x0, interp=0x18bed20, 
    objc=2, objv=0x19b0ce0) at /home/sbron/src/tcl8.6.3/generic/tclEvent.c:1405
#11 0x0000000000416e23 in Dispatch (data=0x19b9db8, interp=0x18bed20, result=0)
    at /home/sbron/src/tcl8.6.3/generic/tclBasic.c:4359
#12 0x0000000000416eab in TclNRRunCallbacks (interp=0x18bed20, result=0, 
    rootPtr=0x0) at /home/sbron/src/tcl8.6.3/generic/tclBasic.c:4392
#13 0x0000000000416779 in Tcl_EvalObjv (interp=0x18bed20, objc=2, 
    objv=0x18fcc40, flags=2097168)
    at /home/sbron/src/tcl8.6.3/generic/tclBasic.c:4123
#14 0x0000000000418bea in TclEvalEx (interp=0x18bed20, 
    script=0x19006e0 "package require http\npackage require tls\n::http::register https 443 ::tls::socket\nhttp::geturl https://core.tcl.tk/\n", numBytes=116, 
    flags=0, line=4, clNextOuter=0x0, 
    outerScript=0x19006e0 "package require http\npackage require tls\n::http::register https 443 ::tls::socket\nhttp::geturl https://core.tcl.tk/\n")
    at /home/sbron/src/tcl8.6.3/generic/tclBasic.c:5261
#15 0x000000000052a6bc in Tcl_FSEvalFileEx (interp=0x18bed20, 
    pathPtr=0x18fc620, encodingName=0x0)
    at /home/sbron/src/tcl8.6.3/generic/tclIOUtil.c:1815
#16 0x00000000005334a9 in Tcl_MainEx (argc=-1, argv=0x7fff36d0a548, 
    appInitProc=0x4114f6 <Tcl_AppInit>, interp=0x18bed20)
    at /home/sbron/src/tcl8.6.3/generic/tclMain.c:417
#17 0x00000000004114ef in main (argc=2, argv=0x7fff36d0a538)
    at /home/sbron/src/tcl8.6.3/unix/tclAppInit.c:84