PR notes

src/Avalonia.Controls/Control.cs

@@ -645,7 +645,7 @@ namespace Avalonia.Controls
 
             if (_focusAdorner != null)
             {
-                var adornerLayer = (Panel)_focusAdorner.Parent;
+                var adornerLayer = (IPanel)_focusAdorner.Parent;
                 adornerLayer.Children.Remove(_focusAdorner);
                 _focusAdorner = null;
             }

src/Avalonia.Controls/TopLevel.cs

@@ -189,7 +189,7 @@ namespace Avalonia.Controls
         protected virtual IRenderTarget CreateRenderTarget()
         {
             if(PlatformImpl == null)
-                throw new InvalidOperationException("PlatformImpl isn't available");
+                throw new InvalidOperationException("Cann't create render target, PlatformImpl is null (might be already disposed)");
             return _renderInterface.CreateRenderTarget(PlatformImpl.Surfaces);
         }
 

src/Avalonia.DotNetFrameworkRuntime/AppBuilder.cs

@@ -83,7 +83,7 @@ namespace Avalonia
         private void LoadAssembliesInDirectory()
         {
             var location = Assembly.GetEntryAssembly().Location;
-            if(location == null)
+            if (string.IsNullOrWhiteSpace(location))
                 return;
             var dir = new FileInfo(location).Directory;
             if (dir == null)