feat：乐团改造

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

@@ -1612,6 +1612,9 @@ public class MusicGroupServiceImpl extends BaseServiceImpl<String, MusicGroup> i
                 price = new BigDecimal(0);
             }
             subtractAmount = subtractAmount.subtract(price);
+            if(BigDecimal.ZERO.compareTo(subtractAmount)<0){
+                subtractAmount = new BigDecimal(0);
+            }
             
             studentRegistrationService.updateUserSurplusCourseFee(userId, musicGroupId, subtractAmount.negate(), reason, operator.getId());
             
@@ -1762,6 +1765,9 @@ public class MusicGroupServiceImpl extends BaseServiceImpl<String, MusicGroup> i
             price = new BigDecimal(0);
         }
         subtractAmount = subtractAmount.subtract(price);
+        if(BigDecimal.ZERO.compareTo(subtractAmount)<0){
+            subtractAmount = new BigDecimal(0);
+        }
 
         studentRegistrationService.updateUserSurplusCourseFee(userId, musicGroupId, subtractAmount.negate(), reason, operator.getId());