Add check to make sure node exists

Author: goldfire

src/howler.core.js

@@ -1678,7 +1678,7 @@
       // If we are using IE and there was network latency we may be clipping
       // audio before it completes playing. Lets check the node to make sure it
       // believes it has completed, before ending the playback.
-      if (!self._webAudio && !self._node.ended) {
+      if (!self._webAudio && self._node && !self._node.ended) {
         setTimeout(self._ended.bind(self, sound), 100);
         return self;
       }