Various updates.

Harmonia.WinUI/Converters/ArtistsToStringConverter.cs

@@ -1,5 +1,6 @@
 using Microsoft.UI.Xaml.Data;
 using System;
+using System.Collections.Generic;
 
 namespace Harmonia.WinUI.Converters;
 
@@ -12,7 +13,7 @@ public partial class ArtistsToStringConverter : IValueConverter
 
     public object Convert(object value, Type targetType, object parameter, string language)
     {
-        if (value is not string[] artists)
+        if (value is not ICollection<string> artists)
             return string.Empty;
 
         return string.Join(" / ", artists);

Harmonia.WinUI/Converters/NullVisibilityConverter.cs

@@ -15,7 +15,7 @@ public sealed partial class NullVisibilityConverter : IValueConverter
     public object Convert(object value, Type targetType, object parameter, string language)
     {
         if (value is not IList list)
-            return Visibility.Collapsed;
+            return value == null ? Visibility.Collapsed : Visibility.Visible;
         
         return list.Count == 0 ? Visibility.Collapsed : Visibility.Visible;
     }