Merge branch 'ExpanderInPopupBug' of https://github.com/mou-haz/UI.WPF.Modern into ExpanderInPopupBug

Author: mou-haz

source/iNKORE.UI.WPF.Modern/Controls/Helpers/ExpanderAnimationsHelper.cs

@@ -304,7 +304,7 @@ private static FrameworkElement GetToAnimateControl(Expander expander)
             {
                 expander.ApplyTemplate();
                 toAnimateControl = expander.Template?.FindName(animationTargetName, expander) as FrameworkElement ??
-                    throw new ArgumentNullException("ToAnimateControl", $"Couldn't find the Border part to animate either update the ExpanderAnimationsHelper.ToAnimateControlName or rename the animation target part to default: {DefaultAnimationTargetPartName}");
+                    throw new ArgumentNullException("ToAnimateControl", $"Couldn't find the part to animate either update the ExpanderAnimationsHelper.ToAnimateControlName or rename the animation target part to default: {DefaultAnimationTargetPartName}");
             }
 
             expander.SetValue(CachedToAnimateControlProperty, toAnimateControl);