chore: Do not allow setting application data path overrides after the…

… application is initialized

src/Uno.UWP/Storage/ApplicationData.cs

@@ -5,6 +5,7 @@
 #pragma warning disable 114 // new keyword hiding
 #pragma warning disable 67 // new keyword hiding
 using System;
+using Uno;
 
 namespace Windows.Storage;
 
@@ -38,6 +39,8 @@ private ApplicationData()
 		_roamingSettingsLazy = new(() => new ApplicationDataContainer(this, "Roaming", ApplicationDataLocality.Roaming));
 
 		InitializePartial();
+
+		WinRTFeatureConfiguration.ApplicationData.IsApplicationDataInitialized = true;
 	}
 
 	partial void InitializePartial();

src/Uno.UWP/WinRTFeatureConfiguration.ApplicationData.cs

@@ -1,33 +1,75 @@
 #nullable enable
 
+using System;
+
 namespace Uno;
 
 partial class WinRTFeatureConfiguration
 {
 	public static class ApplicationData
 	{
 #if __SKIA__
+		private static string? _temporaryFolderPathOverride;
+		private static string? _localCacheFolderPathOverride;
+		private static string? _applicationDataPathOverride;
+
 		/// <summary>
 		/// Allows overriding the root folder path that the application will use
 		/// to store its TempState folder.
 		/// </summary>
 		/// <remarks>Only applies to Skia targets.</remarks>
-		public static string? TemporaryFolderPathOverride { get; set; }
+		public static string? TemporaryFolderPathOverride
+		{
+			get => _temporaryFolderPathOverride;
+			set
+			{
+				EnsureApplicationDataNotInitialized();
+				_temporaryFolderPathOverride = value;
+			}
+		}
 
 		/// <summary>
 		/// Allows overriding the root folder path that the application will use
 		/// to store its LocalCache folder.
 		/// </summary>
 		/// <remarks>Only applies to Skia targets.</remarks>
-		public static string? LocalCacheFolderPathOverride { get; set; }
+		public static string? LocalCacheFolderPathOverride
+		{
+			get => _localCacheFolderPathOverride;
+			set
+			{
+				EnsureApplicationDataNotInitialized();
+				_localCacheFolderPathOverride = value;
+			}
+		}
 
 		/// <summary>
 		/// Allows overriding the root folder that the application will use
 		/// to store its application data folders (LocalFolder, RoamingFolder, etc.).
 		/// Only applies to Skia targets.
 		/// </summary>
 		/// <remarks>Only applies to Skia targets.</remarks>
-		public static string? ApplicationDataPathOverride { get; set; }
+		public static string? ApplicationDataPathOverride
+		{
+			get => _applicationDataPathOverride;
+			set
+			{
+				EnsureApplicationDataNotInitialized();
+				_applicationDataPathOverride = value;
+			}
+		}
+
+		internal static bool IsApplicationDataInitialized { get; set; }
+
+		private static void EnsureApplicationDataNotInitialized()
+		{
+			if (IsApplicationDataInitialized)
+			{
+				throw new InvalidOperationException(
+					"The property was set too late in the application lifecycle." +
+					"Set it in Program.cs, so it is applied before ApplicationData is initialized.");
+			}
+		}
 #endif
 	}
 }