fixed the case where a maximal end componend decomposition is requested for an empty subsystem

Former-commit-id: 96ba0262ce

src/storage/MaximalEndComponentDecomposition.cpp

@@ -65,7 +65,9 @@ namespace storm {
             
             // Initialize the maximal end component list to be the full state space.
             std::list<StateBlock> endComponentStateSets;
+            if(!subsystem.empty()) {
                 endComponentStateSets.emplace_back(subsystem.begin(), subsystem.end());
+            }
             storm::storage::BitVector statesToCheck(numberOfStates);
             
             // The iterator used here should really be a const_iterator.