Fixes logic check for sound asset macros so if the defined field value is an object, we consider it valid, as it's almost certainly an SFXPlaylist or track. This removes some unneeded error spam

Engine/source/T3D/assets/SoundAsset.h

@@ -253,7 +253,7 @@ public: \
          Con::errorf("%s(%s)::_set%s() - sound asset failure\"%s\" due to [%s]", macroText(className), getName(), macroText(name), _in, SoundAsset::getAssetErrstrn(m##name##Asset->getStatus()).c_str());\
          return false; \
       }\
-      else if (!m##name)\
+      else if (!m##name && (m##name##Name != StringTable->EmptyString() && !Sim::findObject(m##name##Name)))\
       {\
          Con::errorf("%s(%s)::_set%s() - Couldn't load sound \"%s\"", macroText(className), getName(), macroText(name), _in);\
          return false;\
@@ -417,7 +417,7 @@ public: \
          Con::errorf("%s(%s)::_set%s(%i) - sound asset failure\"%s\" due to [%s]", macroText(className), getName(), macroText(name),index, _in, SoundAsset::getAssetErrstrn(m##name##Asset[index]->getStatus()).c_str());\
          return false; \
       }\
-      else if (!m##name[index])\
+      else if (!m##name[index] && (m##name##Name[index] != StringTable->EmptyString() && !Sim::findObject(m##name##Name[index])))\
       {\
          Con::errorf("%s(%s)::_set%s(%i) - Couldn't load sound \"%s\"", macroText(className), getName(), macroText(name),index, _in);\
          return false;\