Retry source requests

Handle missing sources
Minor Optimizations
Move thread pool improvement to debug while we fix it

NuGet/NuGetClient.cs

@@ -97,25 +97,43 @@ public class NuGetClient
         return _client.GetFromJsonAsync<SearchResult>(builder.Uri, SerializerOptions)!;
     }
 
-    public static async Task<NuGetClient> CreateFromIndexUrlAsync(string indexUrl)
+    public static async Task<NuGetClient?> CreateFromIndexUrlAsync(string indexUrl)
     {
         var client = new HttpClient(new HttpClientHandler
         {
-            AutomaticDecompression = DecompressionMethods.All
+            AutomaticDecompression = DecompressionMethods.All,
         });
 
-        var index = await client.GetFromJsonAsync<NuGetIndex>(indexUrl, SerializerOptions);
-        
-        var (packageBaseAddress, _, _) = index!.Resources.First(b => b.Type.Id == "PackageBaseAddress");
-        var (registration, _, _) = index.Resources.First(b => b.Type.Id == "RegistrationsBaseUrl");
-        var (search, _, _) = index.Resources.First(b => b.Type.Id == "SearchQueryService");
+        NuGetClient? ngClient = null;
 
-        if (!packageBaseAddress.EndsWith('/'))
-            packageBaseAddress += '/';
-        if (!registration.EndsWith('/'))
-            registration += '/';
+        const int MaxRetries = 10;
 
-        return new NuGetClient(new Uri(indexUrl), client, new Uri(packageBaseAddress), new Uri(registration), new Uri(search));
+        for (var i  = 0; i < MaxRetries; i++)
+        {
+            try
+            {
+                var index = await client.GetFromJsonAsync<NuGetIndex>(indexUrl, SerializerOptions);
+
+                var (packageBaseAddress, _, _) = index!.Resources.First(b => b.Type.Id == "PackageBaseAddress");
+                var (registration, _, _) = index.Resources.First(b => b.Type.Id == "RegistrationsBaseUrl");
+                var (search, _, _) = index.Resources.First(b => b.Type.Id == "SearchQueryService");
+
+                if (!packageBaseAddress.EndsWith('/'))
+                    packageBaseAddress += '/';
+                if (!registration.EndsWith('/'))
+                    registration += '/';
+
+                ngClient = new NuGetClient(new Uri(indexUrl), client, new Uri(packageBaseAddress), new Uri(registration), new Uri(search));
+
+                break;
+            }
+            catch (HttpRequestException ex)
+            {
+                Console.WriteLine(ex.Message);
+            }
+        }
+
+        return ngClient;
     }
 
     public override string ToString() => _index.ToString();