message: fix Idr UBSAN warning
diff: @@ -287,10 +287,10 @@ protected:
  private:
  std::shared_ptr<const LinOp> system_matrix_{};
  std::shared_ptr<const stop::CriterionFactory> stop_criterion_factory_{};
  - size_type subspace_dim_;
  - remove_complex<ValueType> kappa_;
  - bool deterministic_;
  - bool complex_subspace_;
  + size_type subspace_dim_{};
  + remove_complex<ValueType> kappa_{};
  + bool deterministic_{};
  + bool complex_subspace_{};
  };
  