bug修复

src/main/java/com/project/exam/domain/service/impl/BuildExamRecordDomainServiceImpl.java

@@ -116,6 +116,9 @@ public class BuildExamRecordDomainServiceImpl implements BuildExamRecordDomainSe
     }
 
     private String buildeScore(Double score){
+        if (Objects.isNull(score)) {
+            return null;
+        }
         return score == score.longValue() ? String.valueOf(score.longValue()) : String.format("%.2f", score);
     }
 }