Fix a crash if JIT space failed to allocate

Common/CodeBlock.h

@@ -71,6 +71,9 @@ public:
 	// Always clear code space with breakpoints, so that if someone accidentally executes
 	// uninitialized, it just breaks into the debugger.
 	void ClearCodeSpace(int offset) {
+		if (!region) {
+			return;
+		}
 		if (PlatformIsWXExclusive()) {
 			ProtectMemoryPages(region, region_size, MEM_PROT_READ | MEM_PROT_WRITE);
 		}

GPU/Common/VertexDecoderCommon.cpp

@@ -1390,5 +1390,7 @@ VertexDecoderJitCache::VertexDecoderJitCache()
 }
 
 void VertexDecoderJitCache::Clear() {
-	ClearCodeSpace(0);
+	if (g_Config.iCpuCore == (int)CPUCore::JIT) {
+		ClearCodeSpace(0);
+	}
 }