Remove application error (#25882)

Author: jkotalik

src/Servers/IIS/IIS/src/Core/IISHttpContext.cs

@@ -533,7 +533,7 @@ protected async Task FireOnCompleted()
                     }
                     catch (Exception ex)
                     {
-                        ReportApplicationError(ex);
+                        Log.ApplicationError(_logger, ((IHttpConnectionFeature)this).ConnectionId, TraceIdentifier, ex);
                     }
                 }
             }

src/Servers/IIS/IIS/test/Common.FunctionalTests/Inprocess/StartupTests.cs

@@ -968,6 +968,26 @@ public async Task EnvironmentVariableForLauncherArgsIsPreferred(HostingModel hos
             await StartAsync(deploymentParameters);
         }
 
+        [ConditionalFact]
+        [RequiresNewHandler]
+        [MaximumOSVersion(OperatingSystems.Windows, WindowsVersions.Win10_20H1, SkipReason = "Shutdown hangs https://github.com/dotnet/aspnetcore/issues/25107")]
+        public async Task OnCompletedDoesNotFailRequest()
+        {
+            var deploymentParameters = Fixture.GetBaseDeploymentParameters();
+            var deploymentResult = await DeployAsync(deploymentParameters);
+
+            var response = await deploymentResult.HttpClient.GetAsync("/OnCompletedThrows");
+            Assert.True(response.IsSuccessStatusCode);
+
+            StopServer();
+
+            if (deploymentParameters.ServerType == ServerType.IISExpress)
+            {
+                // We can't read stdout logs from IIS as they aren't redirected.
+                Assert.Contains(TestSink.Writes, context => context.Message.Contains("An unhandled exception was thrown by the application."));
+            }
+        }
+
         private static void VerifyDotnetRuntimeEventLog(IISDeploymentResult deploymentResult)
         {
             var entries = GetEventLogsFromDotnetRuntime(deploymentResult);

src/Servers/IIS/IIS/test/testassets/InProcessWebSite/Startup.cs

@@ -1461,6 +1461,16 @@ public Task IncreaseRequestLimit(HttpContext httpContext)
             return Task.CompletedTask;
         }
 
+        public Task OnCompletedThrows(HttpContext httpContext)
+        {
+            httpContext.Response.OnCompleted(() =>
+            {
+                throw new Exception();
+            });
+
+            return Task.CompletedTask;
+        }
+
         internal static readonly HashSet<(string, StringValues, StringValues)> NullTrailers = new HashSet<(string, StringValues, StringValues)>()
         {
             ("NullString", (string)null, (string)null),