Address exception with HTTP proxying (#10616)

* Address exception with HTTP proxying

* update release_notes.md

* Also set forwarding task instead of add

Author: jviau

release_notes.md

@@ -5,3 +5,4 @@
 -->
 - Introduced proper handling in environments where .NET in-proc is not supported.
 - Updated System.Memory.Data reference to 8.0.1
+- Address issue with HTTP proxying throwing `ArgumentException` (#10616)

src/WebJobs.Script.Grpc/Server/DefaultHttpProxyService.cs

@@ -81,14 +81,13 @@ public void StartForwarding(ScriptInvocationContext context, Uri httpUri)
             }
 
             HttpContext httpContext = httpRequest.HttpContext;
-
-            httpContext.Items.Add(ScriptConstants.HttpProxyingEnabled, bool.TrueString);
+            httpContext.Items[ScriptConstants.HttpProxyingEnabled] = bool.TrueString;
 
             // add invocation id as correlation id
             httpRequest.Headers.TryAdd(ScriptConstants.HttpProxyCorrelationHeader, context.ExecutionContext.InvocationId.ToString());
 
             var forwardingTask = _httpForwarder.SendAsync(httpContext, httpUri.ToString(), _messageInvoker, _forwarderRequestConfig).AsTask();
-            context.Properties.Add(ScriptConstants.HttpProxyTask, forwardingTask);
+            context.Properties[ScriptConstants.HttpProxyTask] = forwardingTask;
         }
     }
 }