[Bug] GravatarImageSource throws exception when offline (#1816)

* [Bug] GravatarImageSource throws exception when offline #1770

Fix Nullable

* ConfigureAwait, revert sln

Author: VladislavAntonyuk

samples/XCT.Sample.Android/SplashActivity.cs

@@ -1,4 +1,5 @@
-using Android.App;
+#nullable enable
+using Android.App;
 using Android.Content;
 using Android.Content.PM;
 using Android.OS;

src/CommunityToolkit/Xamarin.CommunityToolkit.UnitTests/Xamarin.CommunityToolkit.UnitTests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp2.1;netcoreapp3.1;net461</TargetFrameworks>
+    <TargetFrameworks>netcoreapp3.1;net461</TargetFrameworks>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 

src/CommunityToolkit/Xamarin.CommunityToolkit/Effects/StatusBar/PlatformStatusBarEffect.ios.cs

@@ -99,9 +99,9 @@ static void UpdateStatusBarAppearance()
 			}
 		}
 
-		static void UpdateStatusBarAppearance(UIWindow window)
+		static void UpdateStatusBarAppearance(UIWindow? window)
 		{
-			var vc = window.RootViewController ?? throw new NullReferenceException(nameof(window.RootViewController));
+			var vc = window?.RootViewController ?? throw new NullReferenceException(nameof(window.RootViewController));
 			while (vc.PresentedViewController != null)
 			{
 				vc = vc.PresentedViewController;

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/GravatarImageSource/Shared/GravatarImageSourceHandler.android.ios.macos.tizen.uwp.wpf.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.IO;
 using System.Net.Http;
 using System.Security.Cryptography;
@@ -12,8 +13,8 @@ namespace Xamarin.CommunityToolkit.UI.Views
 	public partial class GravatarImageSourceHandler
 	{
 		const string requestUriFormat = "https://www.gravatar.com/avatar/{0}?s={1}&d={2}";
-		static readonly Lazy<HttpClient> lazyHttp = new Lazy<HttpClient>(() => new HttpClient());
-		static readonly SemaphoreSlim semaphore = new SemaphoreSlim(1);
+		static readonly Lazy<HttpClient> lazyHttp = new(() => new HttpClient());
+		static readonly SemaphoreSlim semaphore = new(1);
 
 		public static async Task<FileInfo?> LoadInternal(ImageSource imageSource, float scale, string cacheDirectory)
 		{
@@ -26,7 +27,7 @@ public partial class GravatarImageSourceHandler
 				{
 					_ = gis.Email ?? throw new InvalidOperationException($"{nameof(gis.Email)} is not initialized");
 					var imageBytes = await GetGravatarAsync(gis.Email, gis.Size, scale, gis.Default);
-					await SaveImage(cacheFileInfo, imageBytes ?? Array.Empty<byte>());
+					await SaveImage(cacheFileInfo, imageBytes);
 				}
 
 				return cacheFileInfo;
@@ -67,7 +68,7 @@ static async Task<bool> UseCacheFile(bool cachingEnabled, TimeSpan cacheValidity
 			{
 				await semaphore.WaitAsync();
 
-				if (!file.Directory.Exists)
+				if (file.Directory is { Exists: false })
 					file.Directory.Create();
 			}
 			finally
@@ -87,12 +88,20 @@ static string CacheFileName(GravatarImageSource gis, float scale)
 		static async Task<byte[]> GetGravatarAsync(string email, int size, float scale, DefaultGravatar defaultGravatar)
 		{
 			var requestUri = GetGravatarUri(email, size, scale, defaultGravatar);
-			using var response = await lazyHttp.Value.GetAsync(requestUri);
+			try
+			{
+				using var response = await lazyHttp.Value.GetAsync(requestUri);
 
-			if (!response.IsSuccessStatusCode)
-				return Array.Empty<byte>();
+				if (!response.IsSuccessStatusCode)
+					return Array.Empty<byte>();
 
-			return await response.Content.ReadAsByteArrayAsync();
+				return await response.Content.ReadAsByteArrayAsync().ConfigureAwait(false);
+			}
+			catch (Exception e)
+			{
+				Trace.WriteLine(e.Message);
+				return Array.Empty<byte>();
+			}
 		}
 
 		static string GetGravatarUri(string email, int size, float scale, DefaultGravatar defaultGravatar)
@@ -113,10 +122,9 @@ static string GetMd5Hash(string str)
 
 			var sBuilder = new StringBuilder();
 
-			if (hash != null)
+			foreach (var hashByte in hash)
 			{
-				for (var i = 0; i < hash.Length; i++)
-					sBuilder.Append(hash[i].ToString("x2"));
+				sBuilder.Append(hashByte.ToString("x2"));
 			}
 
 			return sBuilder.ToString();

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/MediaElement/iOS/MediaElementRenderer.ios.cs

@@ -312,6 +312,7 @@ void UpdateVolume()
 			if (avPlayerViewController.Player != null)
 				avPlayerViewController.Player.Volume = (float)Element.Volume;
 		}
+
 		void UpdateSpeed()
 		{
 			if (avPlayerViewController.Player != null)

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/Snackbar/SnackBar.ios.macos.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Threading.Tasks;
 using Xamarin.CommunityToolkit.UI.Views.Helpers;
-using Xamarin.CommunityToolkit.UI.Views.Helpers;
 using Xamarin.CommunityToolkit.UI.Views.Options;
 using Xamarin.CommunityToolkit.Views.Snackbar.Helpers;
 using Xamarin.Forms;

src/Markup/Xamarin.CommunityToolkit.Markup.UnitTests/Xamarin.CommunityToolkit.Markup.UnitTests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp2.1;netcoreapp3.1;net461</TargetFrameworks>
+    <TargetFrameworks>netcoreapp3.1;net461</TargetFrameworks>
     <IsPackable>false</IsPackable>
   </PropertyGroup>