[X] fix CollectionItems enumeration

src/Controls/src/Xaml/XamlNode.cs

@@ -208,7 +208,7 @@ public override void Accept(IXamlNodeVisitor visitor, INode parentNode)
 			{
 				foreach (var node in Properties.Values.ToList())
 					node.Accept(visitor, this);
-				foreach (var node in CollectionItems)
+				foreach (var node in CollectionItems.ToList())
 					node.Accept(visitor, this);
 			}
 

src/Controls/tests/Xaml.UnitTests/Issues/Maui17222.xaml.cs

@@ -27,6 +27,7 @@ class Test
 #if DEBUG
 		[SetUp] public void Setup() => AppInfo.SetCurrent(new MockAppInfo());
 		[TearDown] public void TearDown() => AppInfo.SetCurrent(null);
+
 		[Test]
 		public void GetsourceInfo([Values(false)] bool useCompiledXaml)
 		{

src/Controls/tests/Xaml.UnitTests/Issues/Maui17333.xaml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<ResourceDictionary 
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    x:Class="Microsoft.Maui.Controls.Xaml.UnitTests.Maui17333">   
+
+    <OnPlatform x:TypeArguments="x:String"
+        x:Key="RegularFont"
+        Default="OpenSansRegular"
+        />
+
+    <OnPlatform x:TypeArguments="x:String"
+        x:Key="BoldFont"
+        Default="OpenSansSemiBold"
+        />
+
+</ResourceDictionary>

src/Controls/tests/Xaml.UnitTests/Issues/Maui17333.xaml.cs

@@ -0,0 +1,39 @@
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System;
+using Microsoft.Maui.ApplicationModel;
+using Microsoft.Maui.Controls.Core.UnitTests;
+using Microsoft.Maui.Controls.Shapes;
+using Microsoft.Maui.Devices;
+using Microsoft.Maui.Graphics;
+using NUnit.Framework;
+
+namespace Microsoft.Maui.Controls.Xaml.UnitTests;
+
+public partial class Maui17333 : ResourceDictionary
+{
+
+	public Maui17333() => InitializeComponent();
+
+	public Maui17333(bool useCompiledXaml)
+	{
+		//this stub will be replaced at compile time
+	}
+
+	[TestFixture]
+	class Test
+	{
+		[SetUp] public void Setup() => AppInfo.SetCurrent(new MockAppInfo());
+		[TearDown] public void TearDown() => AppInfo.SetCurrent(null);
+
+		[Test]
+		public void CompilerDoesntThrowOnOnPlatform([Values(true)] bool useCompiledXaml)
+		{
+			if (useCompiledXaml)
+			{
+				MockCompiler.Compile(typeof(Maui17333),targetFramework: "net-ios");
+			}
+		}
+	}
+}