Replace NULL with nullptr

core/method_bind.cpp

@@ -108,7 +108,7 @@ MethodBind::MethodBind() {
 	argument_count = 0;
 	default_argument_count = 0;
 #ifdef DEBUG_METHODS_ENABLED
-	argument_types = NULL;
+	argument_types = nullptr;
 #endif
 	_const = false;
 	_returns = false;