fix ThrowIfNotNull

Src/Dlhis.External/Appointment/Services/Implements/AppointmentService.cs

@@ -219,7 +219,7 @@ public class AppointmentService : IAppointmentService
                     })
                     .SingleAsync();
 
-                gainfo.ThrowIfNotNull("501被访人工号不存在");
+                gainfo.ThrowIfNull("501被访人工号不存在");
 
                 //501厂区发送访客预约
                 var httpClient = _httpClientFactory.CreateClient();