Making action selection logging not throw on 404

src/Microsoft.AspNet.Mvc.Core/Logging/DefaultActionSelectorSelectAsyncValues.cs

@@ -75,7 +75,7 @@ namespace Microsoft.AspNet.Mvc.Logging
 
         private string Formatter(ActionDescriptor descriptor)
         {
-            return descriptor.DisplayName;
+            return descriptor?.DisplayName ?? "No action selected";
         }
     }
 }

test/Microsoft.AspNet.Mvc.Core.Test/DefaultActionSelectorSelectAsyncValuesTest.cs

@@ -0,0 +1,30 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.Logging
+{
+    public class DefaultActionSelectorSelectAsyncValuesTest
+    {       
+        [Fact]
+        public void EmptyDefaultActionSelectorSelectAsyncValues_ReturnValue()
+        {
+            // Arrange
+            var logObject = new DefaultActionSelectorSelectAsyncValues();
+
+            // Act
+            var result = logObject.ToString();
+
+            var expected = "DefaultActionSelector.SelectAsync" + Environment.NewLine +
+                "\tActions matching route constraints: " + Environment.NewLine +
+                "\tActions matching action constraints: " + Environment.NewLine +
+                "\tFinal Matches: " + Environment.NewLine +
+                "\tSelected action: No action selected";
+
+            // Assert
+            Assert.Equal(expected, result);
+        }
+    }
+}