fix bugs

stmms-biz/src/main/java/cn/com/qmth/stmms/biz/exam/service/impl/ExamStudentServiceImpl.java

@@ -935,6 +935,9 @@ public class ExamStudentServiceImpl extends BaseQueryService<ExamStudent> implem
      */
     private List<OriginTag> buildOriginTags(ExamStudent student, MarkGroup group, List<ExamQuestion> questions,
             List<ScoreItem> scoreList, boolean withGroupScore) {
+        if (scoreList.size() == 0) {
+            return new LinkedList<>();
+        }
         DecimalFormat format = new DecimalFormat("####.###");
         // 从考生主观题得分中拆解出本大题得分
         double score = 0;