bug is in selecting items control. add failing unit test.

src/Avalonia.Controls/Presenters/CarouselPresenter.cs

@@ -115,11 +115,6 @@ namespace Avalonia.Controls.Presenters
                         var containers = generator.RemoveRange(e.OldStartingIndex, e.OldItems.Count);
                         Panel.Children.RemoveAll(containers.Select(x => x.ContainerControl));
 
-                        if(SelectedIndex >= Items.Count())
-                        {
-                            SelectedIndex = Items.Count() - 1;
-                        }
-
 #pragma warning disable 4014
                         MoveToPage(-1, SelectedIndex);
 #pragma warning restore 4014

tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs

@@ -149,6 +149,34 @@ namespace Avalonia.Controls.UnitTests.Primitives
             Assert.Equal(1, target.SelectedIndex);
         }
 
+        [Fact]
+        public void SelectedIndex_Item_Is_Updated_As_Items_Removed_When_Last_Item_Is_Selected()
+        {
+            var items = new ObservableCollection<string>
+            {
+               "Foo",
+               "Bar",
+               "FooBar"
+            };
+
+            var target = new SelectingItemsControl
+            {
+                Items = items,
+                Template = Template(),
+            };
+
+            target.ApplyTemplate();
+            target.SelectedItem = items[2];
+
+            Assert.Equal(items[2], target.SelectedItem);
+            Assert.Equal(2, target.SelectedIndex);
+
+            items.RemoveAt(0);
+
+            Assert.Equal(items[1], target.SelectedItem);
+            Assert.Equal(1, target.SelectedIndex);
+        }
+
         [Fact]
         public void Setting_SelectedItem_To_Not_Present_Item_Should_Clear_Selection()
         {