message: Add destructor for `MixedIntegrator`.
diff: @@ -25,8 +25,7 @@ template <typename CeedInteg>
  class MixedIntegrator : public ceed::Operator
  {
  #ifdef MFEM_USE_CEED
  - // using ElementKey = std::pair<Element::Type, int>;
  - using ElementKey = std::pair<int, int>;
  + using ElementKey = std::pair<int, int>; //< Element::Type, Order >
  struct key_hash
  {
  std::size_t operator()(const ElementKey& k) const
  @@ -98,7 +97,7 @@ public:
  auto sub_op = new CeedInteg();
  int nelem = *count[value.first];
  sub_op->Assemble(info, fes, ir, nelem, indices, Q);
  - sub_ops.push_back(sub_op); // TODO delete
  + sub_ops.push_back(sub_op);
  CeedCompositeOperatorAddSub(oper, sub_op->GetCeedOperator());
  }
  @@ -106,6 +105,14 @@ public:
  CeedVectorCreate(internal::ceed, ndofs, &u);
  CeedVectorCreate(internal::ceed, ndofs, &v);
  }
  +
  + virtual ~MixedIntegrator()
  + {
  + for (auto sub_op : sub_ops)
  + {
  + delete sub_op;
  + }
  + }
  #endif
  };
  