.NET MVC Sentry logging in OnException

OnException.cs

        public RavenClient raven
        {
            get
            {
                var ravenKey = "raven_key";
                var raven = new RavenClient(ravenKey);
                return raven;
            }
        }


        protected override void OnException(ExceptionContext filterContext)
        {
            if (filterContext == null)
            {
                throw new ArgumentNullException("filterContext");
            }

            if (filterContext.IsChildAction)
            {
                return;
            }

            // If custom errors are disabled, we need to let the normal ASP.NET exception handler
            // execute so that the user can see useful debugging information.
            if (filterContext.ExceptionHandled)
            {
                return;
            }

            Exception exception = filterContext.Exception;

            // Ingnore Exceptions that generate http status codes less than 500
            var httpCode = new HttpException(null, exception).GetHttpCode();
            if (httpCode < 500)
            {
                return;
            }

            // Lambda for pretty output of NameValueCollections
            Func<NameValueCollection, string> formatCollection =
                collection =>
                {
                    return String.Join("\r\n", collection.AllKeys.SelectMany(key =>
                        {
                            return collection.GetValues(key).Select(value => key + "=" + value);
                        }
                    ));
                };


            string controllerName = (string)filterContext.RouteData.Values["controller"];
            string actionName = (string)filterContext.RouteData.Values["action"];
            HandleErrorInfo model = new HandleErrorInfo(filterContext.Exception, controllerName, actionName);

            var tags = new Dictionary<string, string> { { "controller", controllerName } };

            var data = new Dictionary<string, object>();
            data["headers"] = formatCollection(Request.Headers);
            data["controller_name"] = controllerName;
            data["action_name"] = actionName;
            data["url"] = Request.Url;
            data["query_string"] = formatCollection(Request.QueryString);
            data["http_action"] = Request.RequestType;
            data["data"] = Request.Form;
            data["view_data"] = new ViewDataDictionary<HandleErrorInfo>(model);
            data["temp_data"] = filterContext.Controller.TempData;

            raven.CaptureException(exception, tags: tags, extra: data);
        }