message: fix empty mat check
diff: @@ -196,9 +196,9 @@ MFEM_HOST_DEVICE inline
  void MultT(const int height, const int width, const TA *data, const TX *x,
  TY *y)
  {
  - if (width == 0)
  + if (height == 0)
  {
  - for (int row = 0; row < height; row++)
  + for (int row = 0; row < width; row++)
  {
  y[row] = 0.0;
  }
  