message: calib3d/imgproc: add GCGraph::maxFlow() missing empty checks
diff: @@ -152,6 +152,8 @@ void GCGraph<TWeight>::addTermWeights( int i, TWeight sourceW, TWeight sinkW )
  template <class TWeight>
  TWeight GCGraph<TWeight>::maxFlow()
  {
  + CV_Assert(!vtcs.empty());
  + CV_Assert(!edges.empty());
  const int TERMINAL = -1, ORPHAN = -2;
  Vtx stub, *nilNode = &stub, *first = nilNode, *last = nilNode;
  int curr_ts = 0;
  