BililiveRecorder/BililiveRecorder.WPF/Converters/NullValueTemplateSelector.cs

using System.Windows;
using System.Windows.Controls;

#nullable enable
namespace BililiveRecorder.WPF.Converters
{
    internal class NullValueTemplateSelector : DataTemplateSelector
    {
        public DataTemplate? Normal { get; set; }
        public DataTemplate? Null { get; set; }

        public override DataTemplate? SelectTemplate(object item, DependencyObject container) => item is null ? this.Null : this.Normal;
    }
}