fix：收银端计算完优惠价再次添加商品导致实际支付价NaN

kmall-admin/src/main/webapp/js/sale/sale.js

@@ -1920,12 +1920,12 @@ function handle(goodsDetails,operatorType){
 
     if(vm.reduceMoney > 0){
         vm.discountedPrice = vm.discountedPrice + data.discountedPrice + vm.reduceMoney;
-        vm.actualPrice = vm.actualPrice + data.actualPaymentAmount - vm.reduceMoney;
+        vm.actualPrice = new BigNumber(vm.actualPrice).add(new BigNumber(data.actualPaymentAmount)).subtract(new BigNumber(vm.reduceMoney));
         vm.showReduceMoney = vm.showReduceMoney + vm.reduceMoney;
         vm.reduceMoney = 0;
     }else{
         vm.discountedPrice = vm.discountedPrice + data.discountedPrice ;
-        vm.actualPrice = vm.actualPrice + data.actualPaymentAmount ;
+        vm.actualPrice = new BigNumber(vm.actualPrice).add(new BigNumber(data.actualPaymentAmount));
     }
     if(data.sellVolume < 0){
         data.sellVolume = - data.sellVolume;