(gdb) bt
#0  thr_kill () at thr_kill.S:4
#1  0x00000d3cac7ce524 in __raise (s=11) at /usr/src/lib/libc/gen/raise.c:50
#2  0x00000d3cdb356d42 in nsProfileLock::FatalSignalHandler(int, __siginfo*, void*) () at /usr/local/lib/tor-browser/libxul.so
#3  0x00000d3cdbce95e7 in WasmTrapHandler(int, __siginfo*, void*) () at /usr/local/lib/tor-browser/libxul.so
#4  0x00000d3caa902a40 in handle_signal (actp=actp@entry=0xd3ca705b300, sig=sig@entry=11, info=info@entry=0xd3ca705b6f0, ucp=ucp@entry=0xd3ca705b380)
    at /usr/src/lib/libthr/thread/thr_sig.c:299
#5  0x00000d3caa901f0a in thr_sighandler (sig=11, info=0xd3ca705b6f0, _ucp=0xd3ca705b380) at /usr/src/lib/libthr/thread/thr_sig.c:244
#6  0x00000d3ca79a92d3 in <signal handler called> ()
#7  0x00000d3cdc952a0e in RustMozCrash () at /usr/local/lib/tor-browser/libxul.so
#8  0x00000d3cdc9529bf in mozglue_static::panic_hook::h1ffedb8a04334cbc () at /usr/local/lib/tor-browser/libxul.so
#9  0x00000d3cdc9525ec in core::ops::function::Fn::call::hba6988a3b1983d3f () at /usr/local/lib/tor-browser/libxul.so
#10 0x00000d3cdd05574b in std::panicking::rust_panic_with_hook::hfacb7d7659947c2e () at /usr/local/lib/tor-browser/libxul.so
#11 0x00000d3cdd08b6b7 in std::panicking::begin_panic_handler::{{closure}}::h5b399934fca137ab () at /usr/local/lib/tor-browser/libxul.so
#12 0x00000d3cdd08b2e6 in std::sys_common::backtrace::__rust_end_short_backtrace::h2f7f08e2736a04ee () at /usr/local/lib/tor-browser/libxul.so
#13 0x00000d3cdd055302 in rust_begin_unwind () at /usr/local/lib/tor-browser/libxul.so
#14 0x00000d3cdd0dbe03 in core::panicking::panic_fmt::h9429752fdda7682d () at /usr/local/lib/tor-browser/libxul.so
#15 0x00000d3cdcc151f1 in style::stylist::CascadeData::add_rule_list::hc3725032e99d98a0 () at /usr/local/lib/tor-browser/libxul.so
#16 0x00000d3cdcc15421 in style::stylist::CascadeData::add_stylesheet::h05afeb7058046cab () at /usr/local/lib/tor-browser/libxul.so
#17 0x00000d3cdcc15a1c in style::stylist::CascadeData::rebuild::hc5f9cc4108244a5c () at /usr/local/lib/tor-browser/libxul.so
#18 0x00000d3cdcc684b3 in Servo_StyleSet_FlushStyleSheets () at /usr/local/lib/tor-browser/libxul.so
#19 0x00000d3cda85f9c2 in mozilla::ServoStyleSet::UpdateStylist() () at /usr/local/lib/tor-browser/libxul.so
#20 0x00000d3cda8bf8fe in mozilla::PresShell::DoFlushPendingNotifications(mozilla::ChangesToFlush) () at /usr/local/lib/tor-browser/libxul.so
#21 0x00000d3cda896d6b in nsRefreshDriver::Tick(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp, nsRefreshDriver::IsExtraTick) ()
    at /usr/local/lib/tor-browser/libxul.so
#22 0x00000d3cda89cd39 in mozilla::RefreshDriverTimer::TickRefreshDrivers(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp, nsTArray<RefPtr<nsRefreshDriver> >&)
    () at /usr/local/lib/tor-browser/libxul.so
#23 0x00000d3cda89cb61 in mozilla::RefreshDriverTimer::Tick(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp) () at /usr/local/lib/tor-browser/libxul.so
#24 0x00000d3cda89c50a in mozilla::VsyncRefreshDriverTimer::TickRefreshDriver(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp) ()
    at /usr/local/lib/tor-browser/libxul.so
#25 0x00000d3cda89ce6e in mozilla::detail::RunnableFunction<mozilla::VsyncRefreshDriverTimer::RefreshDriverVsyncObserver::NotifyVsync(mozilla::VsyncEvent const&)::{lambda()#1}>::Run() ()
    at /usr/local/lib/tor-browser/libxul.so
#26 0x00000d3cd8016be3 in mozilla::RunnableTask::Run() () at /usr/local/lib/tor-browser/libxul.so
#27 0x00000d3cd7fffbea in mozilla::TaskController::DoExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) () at /usr/local/lib/tor-browser/libxul.so
#28 0x00000d3cd7ffeb2b in mozilla::TaskController::ExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) () at /usr/local/lib/tor-browser/libxul.so
#29 0x00000d3cd8019458 in mozilla::detail::RunnableFunction<mozilla::TaskController::InitializeInternal()::$_0>::Run() () at /usr/local/lib/tor-browser/libxul.so
#30 0x00000d3cd800b96f in nsThread::ProcessNextEvent(bool, bool*) () at /usr/local/lib/tor-browser/libxul.so
#31 0x00000d3cd800ff3e in NS_ProcessNextEvent(nsIThread*, bool) () at /usr/local/lib/tor-browser/libxul.so
#32 0x00000d3cd84be6e8 in mozilla::ipc::MessagePump::Run(base::MessagePump::Delegate*) () at /usr/local/lib/tor-browser/libxul.so
#33 0x00000d3cd84772a8 in MessageLoop::Run() () at /usr/local/lib/tor-browser/libxul.so
#34 0x00000d3cda670339 in nsBaseAppShell::Run() () at /usr/local/lib/tor-browser/libxul.so
#35 0x00000d3cdb2a8cd6 in nsAppStartup::Run() () at /usr/local/lib/tor-browser/libxul.so
#36 0x00000d3cdb367c7c in XREMain::XRE_mainRun() () at /usr/local/lib/tor-browser/libxul.so
#37 0x00000d3cdb3682b7 in XREMain::XRE_main(int, char**, mozilla::BootstrapConfig const&) () at /usr/local/lib/tor-browser/libxul.so
#38 0x00000d3cdb36866c in XRE_main(int, char**, mozilla::BootstrapConfig const&) () at /usr/local/lib/tor-browser/libxul.so
#39 0x00000d348669e651 in main ()
(gdb) q
% pkg iinfo tor-browser
tor-browser-12.0.6_4
% uname -aKU
FreeBSD mowa219-gjp4-8570p-freebsd 15.0-CURRENT FreeBSD 15.0-CURRENT #14 main-n265350-72d97e1dd9cc-dirty: Sat Sep 16 03:50:44 BST 2023     grahamperrin@mowa219-gjp4-8570p-freebsd:/usr/obj/usr/src/amd64.amd64/sys/GENERIC amd64 1500000 1500000
%