core: assign zero after resize in implementations of heap.Interface #26296 (#1841)

core/txpool/list.go

@@ -46,6 +46,7 @@ func (h *nonceHeap) Pop() interface{} {
 	old := *h
 	n := len(old)
 	x := old[n-1]
+	old[n-1] = 0 // avoid memory leak
 	*h = old[0 : n-1]
 	return x
 }

core/types/transaction.go

@@ -704,6 +704,7 @@ func (s *TxByPriceAndTime) Pop() interface{} {
 	old := s.txs
 	n := len(old)
 	x := old[n-1]
+	old[n-1] = nil // avoid memory leak
 	s.txs = old[0 : n-1]
 	return x
 }