fix:计算课酬时，学生人数从课程上取

mec-biz/src/main/java/com/ym/mec/biz/service/impl/TeacherDefaultMusicGroupSalaryServiceImpl.java

@@ -137,7 +137,11 @@ public class TeacherDefaultMusicGroupSalaryServiceImpl extends BaseServiceImpl<L
 										if(studentNum>5){
 											studentNum = 5;
 										}
-										ts.setExpectSalary(new BigDecimal(obj.getDouble(studentNum + "")));
+										if(studentNum==0){
+											ts.setExpectSalary(BigDecimal.ZERO);
+										}else{
+											ts.setExpectSalary(new BigDecimal(obj.getDouble(studentNum + "")));
+										}
 										list.add(ts);
 									}