fixes: PropertySetterInstance

src/Avalonia.Styling/Styling/PropertySetterInstance.cs

@@ -16,14 +16,14 @@ namespace Avalonia.Styling
         private readonly IStyleable _target;
         private readonly StyledPropertyBase<T>? _styledProperty;
         private readonly DirectPropertyBase<T>? _directProperty;
-        private readonly T _value;
+        private readonly T? _value;
         private IDisposable? _subscription;
         private bool _isActive;
 
         public PropertySetterInstance(
             IStyleable target,
             StyledPropertyBase<T> property,
-            T value)
+            T? value)
         {
             _target = target;
             _styledProperty = property;
@@ -57,7 +57,7 @@ namespace Avalonia.Styling
             {
                 if (_styledProperty is object)
                 {
-                    _subscription = _target.SetValue(_styledProperty, _value, BindingPriority.Style);
+                    _subscription = _target.SetValue(_styledProperty!, _value, BindingPriority.Style);
                 }
                 else
                 {

src/Avalonia.Styling/Styling/Setter.cs

@@ -101,7 +101,7 @@ namespace Avalonia.Styling
                 data.result = new PropertySetterInstance<T>(
                     data.target,
                     property,
-                    (T)data.value!);
+                    (T?)data.value);
             }
         }