I guess there is some synchronization missing, JITWidget still calls PPCAnalyst::PPCAnalyzer::Analyze while the emulator is stopped.
To repro (the crash), just run debug build and start/stop a game with JITWidget active.
> DolphinD.exe!Common::swap32(const unsigned char * data) Line 117 C++
DolphinD.exe!Memory::Read_U32(unsigned int address) Line 424 C++
DolphinD.exe!PowerPC::InstructionCache::ReadInstruction(unsigned int addr) Line 152 C++
DolphinD.exe!PowerPC::TryReadInstruction(unsigned int address) Line 419 C++
DolphinD.exe!PPCAnalyst::PPCAnalyzer::Analyze(unsigned int address, PPCAnalyst::CodeBlock * block, std::vector<PPCAnalyst::CodeOp,std::allocator<PPCAnalyst::CodeOp> > * buffer, unsigned __int64 block_size) Line 763 C++
DolphinD.exe!JITWidget::Update() Line 163 C++
DolphinD.exe!QtPrivate::FunctorCall<QtPrivate::IndexesList<>,QtPrivate::List<>,void,void (__cdecl JITWidget::*)(void)>::call(void(JITWidget::*)() f, JITWidget * o, void * * arg) Line 134 C++
DolphinD.exe!QtPrivate::FunctionPointer<void (__cdecl JITWidget::*)(void)>::call<QtPrivate::List<>,void>(void(JITWidget::*)() f, JITWidget * o, void * * arg) Line 168 C++
DolphinD.exe!QtPrivate::QSlotObject<void (__cdecl JITWidget::*)(void),QtPrivate::List<>,void>::impl(int which, QtPrivate::QSlotObjectBase * this_, QObject * r, void * * a, bool * ret) Line 397 C++
Qt5Cored.dll!00007ffa2eab5538() Unknown
Qt5Cored.dll!00007ffa2eaf04de() Unknown
Qt5Cored.dll!00007ffa2eaefd88() Unknown
DolphinD.exe!Settings::EmulationStateChanged(Core::State _t1) Line 514 C++
DolphinD.exe!Settings::{ctor}::__l2::void <lambda>(Core::State)::__l2::<lambda>() Line 38 C++
DolphinD.exe!QtPrivate::FunctorCall<QtPrivate::IndexesList<>,QtPrivate::List<>,void,void <lambda>(void) >::call(Settings::{ctor}::__l2::void <lambda>(Core::State)::__l2::void <lambda>(void) & f, void * * arg) Line 128 C++
DolphinD.exe!QtPrivate::Functor<void <lambda>(void),0>::call<QtPrivate::List<>,void>(Settings::{ctor}::__l2::void <lambda>(Core::State)::__l2::void <lambda>(void) & f, void * __formal, void * * arg) Line 239 C++
DolphinD.exe!QtPrivate::QFunctorSlotObject<void <lambda>(void),0,QtPrivate::List<>,void>::impl(int which, QtPrivate::QSlotObjectBase * this_, QObject * r, void * * a, bool * ret) Line 427 C++
Qt5Cored.dll!00007ffa2eab5538() Unknown
Qt5Cored.dll!00007ffa2eaf97b6() Unknown
Qt5Cored.dll!00007ffa2eaf220f() Unknown
Qt5Widgetsd.dll!00007ffa2cd5baae() Unknown
Qt5Widgetsd.dll!00007ffa2cd5652f() Unknown
Qt5Cored.dll!00007ffa2ea9c826() Unknown
Qt5Cored.dll!00007ffa2eaa78d2() Unknown
Qt5Cored.dll!00007ffa2ea9e1cd() Unknown
Qt5Cored.dll!00007ffa2eb58bba() Unknown
qwindowsd.dll!00007ffa581166f4() Unknown
Qt5Cored.dll!00007ffa2eb5693b() Unknown
user32.dll!UserCallWinProcCheckWow() Unknown
user32.dll!DispatchMessageWorker() Unknown
Qt5Cored.dll!00007ffa2eb572cd() Unknown
qwindowsd.dll!00007ffa581166b4() Unknown
Qt5Cored.dll!00007ffa2ea96a33() Unknown
Qt5Cored.dll!00007ffa2ea96c6e() Unknown
Qt5Cored.dll!00007ffa2ea9a33f() Unknown
Qt5Guid.dll!00007ffa2d905ca8() Unknown
Qt5Widgetsd.dll!00007ffa2cd55efa() Unknown
DolphinD.exe!main(int argc, char * * argv) Line 219 C++
DolphinD.exe!WinMain(HINSTANCE__ * __formal, HINSTANCE__ * __formal, char * __formal, int __formal) Line 104 C++
DolphinD.exe!invoke_main() Line 107 C++
DolphinD.exe!__scrt_common_main_seh() Line 288 C++
DolphinD.exe!__scrt_common_main() Line 331 C++
DolphinD.exe!WinMainCRTStartup() Line 17 C++
kernel32.dll!BaseThreadInitThunk() Unknown
ntdll.dll!RtlUserThreadStart() Unknown