Add formula in parse exception for easier debugging

src/storm-parsers/parser/FormulaParser.cpp

@@ -88,7 +88,7 @@ namespace storm {
             try {
                 // Start parsing.
                 bool succeeded = qi::phrase_parse(iter, last, *grammar, storm::spirit_encoding::space_type() | qi::lit("//") >> *(qi::char_ - (qi::eol | qi::eoi)) >> (qi::eol | qi::eoi), result);
-                STORM_LOG_THROW(succeeded, storm::exceptions::WrongFormatException, "Could not parse formula.");
+                STORM_LOG_THROW(succeeded, storm::exceptions::WrongFormatException, "Could not parse formula: " << formulaString);
                 STORM_LOG_DEBUG("Parsed formula successfully.");
             } catch (qi::expectation_failure<PositionIteratorType> const& e) {
                 STORM_LOG_THROW(false, storm::exceptions::WrongFormatException, e.what_);