catch uninit access on wrong formula type

src/storm/logic/OperatorFormula.cpp

@@ -15,6 +15,7 @@ namespace storm {
         }
         
         ComparisonType OperatorFormula::getComparisonType() const {
+            STORM_LOG_ASSERT(operatorInformation.bound.is_initialized(), "Cannot get Formula comparison type (has no bound?)");
             return operatorInformation.bound.get().comparisonType;
         }