如果结算金额为0，减去优惠金额后为负数，还设置为0

jsowell-pile/src/main/java/com/jsowell/pile/service/programlogic/AbstractProgramLogic.java

@@ -895,6 +895,10 @@ public abstract class AbstractProgramLogic implements InitializingBean {
 
         // 更新结算金额  结算金额 = 消费金额 - 虚拟金额 - 优惠金额
         BigDecimal newSettleAmount = orderBasicInfo.getSettleAmount().subtract(discountAmount);
+        if (newSettleAmount.compareTo(BigDecimal.ZERO) < 0) {
+            // 如果结算金额为0，减去优惠金额后为负数，还设置为0
+            newSettleAmount = BigDecimal.ZERO;
+        }
         orderBasicInfo.setSettleAmount(newSettleAmount);
 
         // 优惠后总消费金额 = 折扣后电费 + 折扣后服务费