优化

Tiobon.Core.Common/Helper/ExamHelper.cs

@@ -59,6 +59,7 @@ public class ExamHelper
                         var content = recordAnswers.Where(x => x.ExamRecordDetailId == detail.Id).First().AnswerContent;
                         var count1 = completionAnswers1.Count;
 
+                        if (!content.IsNull())
                             for (int i = 0; i < completionAnswers1.Count; i++)
                                 if (content.IndexOf(completionAnswers1[i].AnswerContent) > -1)
                                     count1--;