- added explicit clearing of global VM stask

When exception is thrown from JITed code, VM stask isn't cleared during unwinding
It needs to be clear explicitly to avoid memory leaks and references to destructed objects on shutdown

https://forum.zdoom.org/viewtopic.php?t=66172

src/d_main.cpp

@@ -984,6 +984,7 @@ void D_ErrorCleanup ()
 	}
 	if (gamestate == GS_INTERMISSION) gamestate = GS_DEMOSCREEN;
 	insave = false;
+	ClearGlobalVMStack();
 }
 
 //==========================================================================

src/playsim/dthinker.cpp

@@ -250,6 +250,7 @@ void FThinkerCollection::DestroyAllThinkers()
 	GC::FullGC();
 	if (error)
 	{
+		ClearGlobalVMStack();
 		I_Error("DestroyAllThinkers failed");
 	}
 }

src/scripting/vm/vm.h

@@ -110,6 +110,8 @@ public:
 void ThrowAbortException(EVMAbortException reason, const char *moreinfo, ...);
 void ThrowAbortException(VMScriptFunction *sfunc, VMOP *line, EVMAbortException reason, const char *moreinfo, ...);
 
+void ClearGlobalVMStack();
+
 struct VMReturn
 {
 	void *Location;

src/scripting/vm/vmframe.cpp

@@ -715,6 +715,14 @@ void ThrowVMException(VMException *x)
 #endif
 
 
+void ClearGlobalVMStack()
+{
+	while (GlobalVMStack.PopFrame() != nullptr)
+	{
+	}
+}
+
+
 ADD_STAT(VM)
 {
 	double added = 0;