fix：修正直穿错误

Projects/永冠OPP/WCS.Service/Extensions/DeviceExtension.cs

@@ -131,7 +131,7 @@ namespace WCS.Service.Extensions
             var a = Items.Where(v => v.Data2.Status.HasFlag(IstationStatus.光电状态) && v.Data2.Tasknum > 10000)
                         .Where(v => v.Entity.CODE.ToShort() != v.Data2.Goodsend && v.Data2.Goodsend != 0)
                         .ToList();
-            return a.Count == 0 ? new List<Device<IStation520, IStation521, IStation523>>() : a;
+            return a.Count == 0 ? null : a;
         }
 
         /// <summary>