System.NullReferenceException: Object reference not set to an instance of an object. at EscoraPub.Components.Courses.Attendees.AttendeeForm.FiltraTarifa() in D:\Prog\EscoraPub\Components\Courses\Attendees\AttendeeForm.razor.cs:line 951 at EscoraPub.Components.Courses.Attendees.AttendeeForm.OnSelGroup() in D:\Prog\EscoraPub\Components\Courses\Attendees\AttendeeForm.razor.cs:line 639 at EscoraPub.Components.Courses.Attendees.AttendeeForm.OnParametersSetAsync() in D:\Prog\EscoraPub\Components\Courses\Attendees\AttendeeForm.razor.cs:line 346