clarified error message, as the reward models are present (according to output) but simply empty

src/storm/modelchecker/prctl/helper/SparseMdpPrctlHelper.cpp

@@ -919,7 +919,7 @@ namespace storm {
             template<typename RewardModelType>
             MDPSparseModelCheckingHelperReturnType<ValueType> SparseMdpPrctlHelper<ValueType>::computeReachabilityRewards(Environment const& env, storm::solver::SolveGoal<ValueType>&& goal, storm::storage::SparseMatrix<ValueType> const& transitionMatrix, storm::storage::SparseMatrix<ValueType> const& backwardTransitions, RewardModelType const& rewardModel, storm::storage::BitVector const& targetStates, bool qualitative, bool produceScheduler, ModelCheckerHint const& hint) {
                 // Only compute the result if the model has at least one reward this->getModel().
-                STORM_LOG_THROW(!rewardModel.empty(), storm::exceptions::InvalidPropertyException, "Missing reward model for formula. Skipping formula.");
+                STORM_LOG_THROW(!rewardModel.empty(), storm::exceptions::InvalidPropertyException, "Reward model for formula is empty. Skipping formula.");
                 return computeReachabilityRewardsHelper(env, std::move(goal), transitionMatrix, backwardTransitions,
                                                         [&rewardModel] (uint_fast64_t rowCount, storm::storage::SparseMatrix<ValueType> const& transitionMatrix, storm::storage::BitVector const& maybeStates) {
                                                             return rewardModel.getTotalRewardVector(rowCount, transitionMatrix, maybeStates);

src/storm/modelchecker/prctl/helper/SymbolicMdpPrctlHelper.cpp

@@ -202,7 +202,7 @@ namespace storm {
             template<storm::dd::DdType DdType, typename ValueType>
             std::unique_ptr<CheckResult> SymbolicMdpPrctlHelper<DdType, ValueType>::computeCumulativeRewards(Environment const& env, OptimizationDirection dir, storm::models::symbolic::NondeterministicModel<DdType, ValueType> const& model, storm::dd::Add<DdType, ValueType> const& transitionMatrix, RewardModelType const& rewardModel, uint_fast64_t stepBound) {
                 // Only compute the result if the model has at least one reward this->getModel().
-                STORM_LOG_THROW(!rewardModel.empty(), storm::exceptions::InvalidPropertyException, "Missing reward model for formula. Skipping formula.");
+                STORM_LOG_THROW(!rewardModel.empty(), storm::exceptions::InvalidPropertyException, "Reward model for formula is empty. Skipping formula.");
                 
                 // Compute the reward vector to add in each step based on the available reward models.
                 storm::dd::Add<DdType, ValueType> totalRewardVector = rewardModel.getTotalRewardVector(transitionMatrix, model.getColumnVariables());