refactor(menu-item): add null check of the Id parameter

Author: desmondinho

docs/LumexUI.Docs.Client/Pages/Components/Dropdown/Examples/ColorsVariants.razor

@@ -41,7 +41,6 @@
 
 @code {
     private ThemeColor _color = ThemeColor.Default;
-    private MenuVariant _variant = MenuVariant.Solid;
 
     private Task TriggerAsync( string id )
     {
@@ -57,7 +56,7 @@
             MenuVariant.Flat => Variant.Flat,
             MenuVariant.Shadow => Variant.Shadow,
             MenuVariant.Light => Variant.Light,
-            _ => Variant.Solid
+            _ => throw new NotSupportedException()
         };
     }
 }

src/LumexUI/Components/Menu/MenuItem.razor.cs

@@ -116,6 +116,12 @@ protected override void OnInitialized()
 	/// <inheritdoc />
 	protected override void OnParametersSet()
 	{
+		if( Id is null )
+		{
+			throw new InvalidOperationException(
+				$"{GetType()} requires a value for the {nameof( Id )} parameter." );
+		}
+
 		_disabled = Disabled || Menu.DisabledItems?.Contains( Id ) is true;
 
 		var menuItem = Styles.MenuItem.Style( TwVariant );