Specific C# code crashes the oxidizer

The following code crashes the oxydizer:

private async Task<TriviaQuestion> NextQuestionAsync(string userId)
{
var lastQuestionId = await this.db.TriviaAnswers
    .Where(a => a.UserId == userId)
    .GroupBy(a => a.QuestionId)
    .Select(g => new { QuestionId = g.Key, Count = g.Count() })
    .OrderByDescending(q => new { q.Count, QuestionId = q.QuestionId })
    .Select(q => q.QuestionId)
    .FirstOrDefaultAsync();

var questionsCount = await this.db.TriviaQuestions.CountAsync();

var nextQuestionId = (lastQuestionId % questionsCount) + 1;
return await this.db.TriviaQuestions.FindAsync(CancellationToken.None, nextQuestionId); 
}

Thanks, logged as bugs://85674

bugs://85674 got closed with status fixed.