Couple more minor warning fixes.

Core/HLE/sceKernelThread.cpp

@@ -2709,7 +2709,7 @@ void ActionAfterCallback::run(MipsCall &call) {
 // Returns true if any callbacks were processed on the current thread.
 bool __KernelCheckThreadCallbacks(Thread *thread, bool force)
 {
-	if (!thread->isProcessingCallbacks && !force)
+	if (!thread || (!thread->isProcessingCallbacks && !force))
 		return false;
 
 	for (int i = 0; i < THREAD_CALLBACK_NUM_TYPES; i++) {

Core/HLE/sceMpeg.cpp

@@ -1403,7 +1403,7 @@ int sceMp3Decode(u32 mp3, u32 outPcmPtr)
 	// TODO: Actually decode the data
 #ifdef _DEBUG
 	char fileName[256];
-	sprintf(fileName, "%i.mp3", ctx->mp3StreamPosition);
+	sprintf(fileName, "%lli.mp3", ctx->mp3StreamPosition);
 
 	FILE * file = fopen(fileName, "wb");
 	if(file) {