Fix crash when playing uninitialized audio source

#2441

Source/Engine/Audio/AudioSource.cpp

@@ -152,12 +152,17 @@ void AudioSource::Play()
                 RequestStreamingBuffersUpdate();
         }
     }
-    else
+    else if (SourceIDs.HasItems())
     {
         // Play it right away
         SetNonStreamingBuffer();
         PlayInternal();
     }
+    else
+    {
+        // Source was nt properly added to the Audio Backend
+        LOG(Warning, "Cannot play unitialized audio source.");
+    }
 }
 
 void AudioSource::Pause()