check for empty heaps

source/tensor/XHeap.cpp

@@ -120,7 +120,7 @@ _XINLINE_ void XHeap<hType, T>::ReplaceTop(HeapNode<T> node)
 template<HeapType hType, typename T>
 _XINLINE_ HeapNode<T> XHeap<hType, T>::Pop()
 {
-    //CheckNTErrors((size > 0), "Empty heap!");
+    CheckNTErrors(count > 0, "Empty heap!");
     HeapNode<T> node = items[0];
     items[0] = items[count - 1];
     count--;