When a SPA dev server (or prerendering build) takes too long to start up, only fail current request, not future requests. Fixes #1447

src/Microsoft.AspNetCore.SpaServices.Extensions/Util/TaskTimeoutExtensions.cs

@@ -0,0 +1,35 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.SpaServices.Extensions.Util
+{
+    internal static class TaskTimeoutExtensions
+    {
+        public static async Task WithTimeout(this Task task, TimeSpan timeoutDelay, string message)
+        {
+            if (task == await Task.WhenAny(task, Task.Delay(timeoutDelay)))
+            {
+                task.Wait(); // Allow any errors to propagate
+            }
+            else
+            {
+                throw new TimeoutException(message);
+            }
+        }
+
+        public static async Task<T> WithTimeout<T>(this Task<T> task, TimeSpan timeoutDelay, string message)
+        {
+            if (task == await Task.WhenAny(task, Task.Delay(timeoutDelay)))
+            {
+                return task.Result;
+            }
+            else
+            {
+                throw new TimeoutException(message);
+            }
+        }
+    }
+}