--- /dev/null
+Actually crashes as follows, minimal reproducer via `jsc':
+
+$ /usr/pkg/libexec/webkit2gtk-4.0/jsc
+Segmentation fault (core dumped)
+
+...and:
+
+$ gdb -core jsc.core /usr/pkg/libexec/webkit2gtk-4.0/jsc
+Reading symbols from /usr/pkg/libexec/webkit2gtk-4.0/jsc...
+(No debugging symbols found in /usr/pkg/libexec/webkit2gtk-4.0/jsc)
+[New process 7226]
+[New process 19274]
+Core was generated by `jsc'.
+Program terminated with signal SIGSEGV, Segmentation fault.
+#0 0x00007b211f18589d in JSC::MarkedBlock::Handle::Handle(JSC::Heap&, JSC::AlignedMemoryAllocator*, void*) () from /usr/pkg/lib/libjavascriptcoregtk-4.0.so.18
+[Current thread is 1 (process 7226)]
+(gdb) bt
+#0 0x00007b211f18589d in JSC::MarkedBlock::Handle::Handle(JSC::Heap&, JSC::AlignedMemoryAllocator*, void*) () from /usr/pkg/lib/libjavascriptcoregtk-4.0.so.18
+#1 0x00007b211f18597b in JSC::MarkedBlock::tryCreate(JSC::Heap&, JSC::AlignedMemoryAllocator*) () from /usr/pkg/lib/libjavascriptcoregtk-4.0.so.18
+#2 0x00007b211f15849a in JSC::BlockDirectory::tryAllocateBlock(JSC::Heap&) () from /usr/pkg/lib/libjavascriptcoregtk-4.0.so.18
+#3 0x00007b211f18228e in JSC::LocalAllocator::allocateSlowCase(JSC::Heap&, JSC::GCDeferralContext*, JSC::AllocationFailureMode) () from /usr/pkg/lib/libjavascriptcoregtk-4.0.so.18
+#4 0x00007b211fc7163c in void* JSC::allocateCell<JSC::Structure>(JSC::VM&, unsigned long) () from /usr/pkg/lib/libjavascriptcoregtk-4.0.so.18
+#5 0x00007b211f5ba3ad in JSC::VM::VM(JSC::VM::VMType, JSC::HeapType, WTF::RunLoop*, bool*) () from /usr/pkg/lib/libjavascriptcoregtk-4.0.so.18
+#6 0x00007b211f5bcd64 in JSC::VM::create(JSC::HeapType, WTF::RunLoop*) () from /usr/pkg/lib/libjavascriptcoregtk-4.0.so.18
+#7 0x0000000050219366 in int runJSC<jscmain(int, char**)::{lambda(JSC::VM&, GlobalObject*, bool&)#1}>(CommandLine const&, bool, jscmain(int, char**)::{lambda(JSC::VM&, GlobalObject*, bool&)#1} const&) [clone .constprop.0] ()
+#8 0x000000005021ad2b in jscmain(int, char**) ()
+#9 0x000000005021be21 in main ()