运费计算：BUG修复

app/Services/OwnerPriceOperationService.php

@@ -100,7 +100,7 @@ class OwnerPriceOperationService
         }else{
             foreach ($items as $item){
                 $item["owner_price_operation_id"] = $copyModel->id;
-                $item["discount_price"] = implode(",",$item["discount_price"] ?? []);
+                $item["discount_price"] = implode(",",$item["discount_price"] ?? []) ?? null;
                 $insert[] = $item;
             }
         }