卷库管理中，大题下面的小题删除完成后，无法重新添加小题bug，已修改

cqb-paper/src/main/java/com/qmth/cqb/paper/service/impl/PaperServiceImpl.java

@@ -786,8 +786,14 @@ public class PaperServiceImpl implements PaperService{
         List<PaperDetailUnit> saveUnits = new ArrayList<PaperDetailUnit>();
         for (Question ques : questions) {
             PaperDetailUnit pdu = new PaperDetailUnit(paper,paperDetail,ques);
-            pdu.setNumber(paperDetailUnit.getNumber());//设置为大题中最大的number
-            pdu.setScore(paperDetailUnit.getScore());
+            //如果大题没有小题，取导入的试题分数
+            if(paperDetailUnit == null){
+            	pdu.setNumber(1);
+            	pdu.setScore(ques.getScore());
+            }else {
+            	pdu.setNumber(paperDetailUnit.getNumber());//设置为大题中最大的number
+            	pdu.setScore(paperDetailUnit.getScore());
+			}
             //处理套题
             if(pdu.getQuestionType() == QuesStructType.NESTED_ANSWER_QUESTION){
                 List<Question> subQuestions = ques.getSubQuestions();