fix 补充提醒

Src/Dlhis.Basic/WorkGrids/Services/Implements/WorkGridScheduleService.cs

@@ -62,6 +62,8 @@ public class WorkGridScheduleService : IWorkGridScheduleService
         workGrid.ThrowIfNull("工作网格不存在");
 
         var timeSetting = await _dbContext.Queryable<WorkGridTimePeriodEntity>().Where(x => x.Type == request.PeriodType).Select(x => new { x.Start, x.Before }).SingleAsync();
+        timeSetting.ThrowIfNull("工作网格时间尚未配置,无法操作");
+        
         var currentLimit = request.Date.ToDateTime(timeSetting.Start.Add(-TimeSpan.FromSeconds(timeSetting.Before)));
         (DateTime.Now >= currentLimit).ThrowIfTrue("当前时间不可修改排班信息");