Add detail to InvalidOperationException in Exception Handler Middleware (#22858)

Author: scottaddie

src/Middleware/Diagnostics/src/Resources.resx

@@ -248,7 +248,7 @@
     <value>Environment:</value>
   </data>
   <data name="ExceptionHandlerOptions_NotConfiguredCorrectly" xml:space="preserve">
-    <value>An error occurred when configuring the exception handler middleware. Either the 'ExceptionHandlingPath' or the 'ExceptionHandler' option must be set in 'UseExceptionHandler()'.</value>
+    <value>An error occurred when configuring the exception handler middleware. Either the 'ExceptionHandlingPath' or the 'ExceptionHandler' property must be set in 'UseExceptionHandler()'. Alternatively, set one of the aforementioned properties in 'Startup.ConfigureServices' as follows: 'services.Configure&lt;ExceptionHandlerOptions&gt;(options =&gt; { ... });'.</value>
   </data>
   <data name="ErrorPageHtml_NoRouteValues" xml:space="preserve">
     <value>No route values.</value>
@@ -280,4 +280,4 @@
   <data name="ErrorPageHtml_NameColumn" xml:space="preserve">
     <value>Name</value>
   </data>
-</root>
+</root>

src/Middleware/Diagnostics/test/UnitTests/ExceptionHandlerTest.cs

@@ -406,8 +406,9 @@ public void UsingExceptionHandler_ThrowsAnException_WhenExceptionHandlingPathNot
             var exception = Assert.Throws<InvalidOperationException>(() => new TestServer(builder));
 
             // Assert
-            Assert.Equal($"An error occurred when configuring the exception handler middleware. " +
-                $"Either the 'ExceptionHandlingPath' or the 'ExceptionHandler' option must be set in 'UseExceptionHandler()'.",
+            Assert.Equal("An error occurred when configuring the exception handler middleware. " +
+                "Either the 'ExceptionHandlingPath' or the 'ExceptionHandler' property must be set in 'UseExceptionHandler()'. " +
+                "Alternatively, set one of the aforementioned properties in 'Startup.ConfigureServices' as follows: 'services.Configure<ExceptionHandlerOptions>(options => { ... });'.",
                 exception.Message);
         }
     }