ASP.NET MVC Exception Handler Attribute

using SecurityEssentials.Core.Identity;
using Serilog;
using System;
using System.Web;
using System.Web.Mvc;

namespace SecurityEssentials.Core.Attributes
{
    public class ExceptionHandlerAttribute : FilterAttribute, IExceptionFilter
    {
        private readonly IUserIdentity _userIdentity;

        public ExceptionHandlerAttribute() : this(new UserIdentity())
        { }

        public ExceptionHandlerAttribute(IUserIdentity userIdentity)
        {
            _userIdentity = userIdentity ?? throw new ArgumentNullException(nameof(userIdentity));
        }

        public void OnException(ExceptionContext filterContext)
        {
            if (!filterContext.ExceptionHandled)
            {
                string action = filterContext.RouteData.Values["action"].ToString();
                string controller = filterContext.RouteData.Values["controller"].ToString();
                Requester requester = _userIdentity.GetRequester(filterContext.Controller as Controller);

                if (filterContext.Exception is HttpRequestValidationException)
                {
                    // SECURE: Log XSS Attempt
                    requester.AppSensorDetectionPoint = Constants.AppSensorDetectionPointKind.Ae1;
                    Log.Logger.Information("Failed XSS attempt on controller {controller} and action {action}", controller, action);
                }
                else
                {
                    Log.Logger.Information("Error on controller {controller} and action {action} by requester {@requester}", controller,
                                           action, requester);
#if !DEBUG
                    filterContext.Result = new RedirectResult("/Error/Index/");
                    filterContext.ExceptionHandled = true;
                    filterContext.HttpContext.ClearError();
#endif
                }
            }
        }
    }
}