При таком коде
Quiz quiz = quizRepository.findOne(id);
if (quiz == null) throw new NoSuchQuizException(id);// must 404
получаю
{"status": 500,"code": 500,
"message": "FBI is interested in your talents!",
"developerMessage": "could not extract ResultSet; SQL [n/a]; nested exception is org.hibernate.exception.SQLGrammarException: could not extract ResultSet",
"moreInfoUrl": "mailto:support@javarush.ru"}
А при таком
Quiz quiz = null;
try{
    quiz = quizRepository.findOne(id);
} catch (Exception ignore){

}
if (quiz == null) throw new NoSuchQuizException(id);
Все нормально получаю свой 404

{"status": 404,"code": 404,
"message": "No such Quiz",
"developerMessage": "Quiz with id: 3 is not found on the Database",
"moreInfoUrl": "mailto:support@javarush.ru"}