message: Vector::operator* of size 0 fix
diff: @@ -1017,6 +1017,7 @@ static double hipVectorDot(const int N, const double *X, const double *Y)
  double Vector::operator*(const Vector &v) const
  {
  MFEM_ASSERT(size == v.size, "incompatible Vectors!");
  + if (size == 0) { return 0.0; }
  const bool use_dev = UseDevice() || v.UseDevice();
  #if defined(MFEM_USE_CUDA) || defined(MFEM_USE_HIP) || defined(MFEM_USE_OPENMP)
  