message: Check for valid return value of MultiMat::getFieldIdx() (idx != -1)
diff: @@ -694,6 +694,9 @@ MultiMat::Field2D<T, BSetType> MultiMat::get2dField(const std::string& field_nam
  //create instance of that map
  int fi = getFieldIdx(field_name);
  +
  + if(fi < 0) throw std::invalid_argument("No field with this name is found");
  +
  BSetType* bi_set =
  (BSetType*)this->get_mapped_biSet(m_fieldDataLayoutVec[fi],
  m_fieldSparsityLayoutVec[fi]);
  @@ -713,8 +716,13 @@ MultiMat::DenseField2D<T> MultiMat::getDense2dField(const std::string& field_nam
  auto& bmap = get2dField<T>(field_name);
  //create instance of that map
  + int fieldIdx = getFieldIdx(field_name);
  +
  + if(fieldIdx < 0)
  + throw std::invalid_argument("No field with this name is found");
  +
  ProductSetType* prod_set;
  - if(m_fieldDataLayoutVec[getFieldIdx(field_name)] == DataLayout::CELL_DOM)
  + if(m_fieldDataLayoutVec[fieldIdx] == DataLayout::CELL_DOM)
  prod_set = m_cellMatProdSet;
  else
  prod_set = m_matCellProdSet;
  