DdJaniModelBuilder: Added proper error message in case a bounded integer variable only has an upper or a lower bound.

src/storm/builder/DdJaniModelBuilder.cpp

@@ -434,6 +434,8 @@ namespace storm {
             }
             
             void createVariable(storm::jani::BoundedIntegerVariable const& variable, CompositionVariables<Type, ValueType>& result) {
+                STORM_LOG_THROW(variable.hasLowerBound(), storm::exceptions::NotSupportedException, "DdJaniModelBuilder only supports bounded variables. Variable " << variable.getName() << " has no lower bound.");
+                STORM_LOG_THROW(variable.hasUpperBound(), storm::exceptions::NotSupportedException, "DdJaniModelBuilder only supports bounded variables. Variable " << variable.getName() <<" has no upper bound.");
                 int_fast64_t low = variable.getLowerBound().evaluateAsInt();
                 int_fast64_t high = variable.getUpperBound().evaluateAsInt();
                 std::pair<storm::expressions::Variable, storm::expressions::Variable> variablePair = result.manager->addMetaVariable(variable.getExpressionVariable().getName(), low, high);