Ensures from contains cloned element before trying to remove it

This should close #26.

Author: tplaner

angular-legacy-sortable.js

@@ -115,7 +115,10 @@
 								if (evt.clone) {
 									removed = angular.copy(removed);
 									prevItems.splice(Sortable.utils.index(evt.clone, sortable.options.draggable), 0, prevItems.splice(oldIndex, 1)[0]);
-									evt.from.removeChild(evt.clone);
+
+									if (evt.from.contains(evt.clone)) {
+										evt.from.removeChild(evt.clone);
+									}
 								}
 								else {
 									prevItems.splice(oldIndex, 1);