asp.net核心中的电子邮件/日志未处理的全局异常

Question

我正在全球范围内处理asp.net核心中的未处理异常。下面的代码可以很好地处理异常情况。但是在出现404错误时无法登录。

https://docs.microsoft.com/en-us/aspnet/core/fundamentals/error-handling?view=aspnetcore-2.2

 public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            app.UseMiddleware<ExceptionHandlerMiddleware>();


            app.UseStaticFiles();
            app.UseCookiePolicy();
            app.UseMvc();

        }


public class ExceptionHandlerMiddleware
    {
        private readonly RequestDelegate _next;

        public ExceptionHandlerMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        public async Task Invoke(HttpContext httpContext)
        {
            try
            {
                await _next(httpContext);
                if (httpContext.Response.StatusCode ==(int) HttpStatusCode.NotFound)
                {
                    var feature = httpContext.Features.Get<IExceptionHandlerFeature>();
/// I am getting null here. I don't know why
                    //ExceptionManager.ProcessException(feature.Error);
                }
            }
            catch (Exception ex)
            {
                ExceptionManager.ProcessException(ex);
                httpContext.Response.Redirect("/Error");
            }
        }
    }``` 

My expected result is log the exception into db and redirect to a static error html page whether it is 404 error Or it is unhanded exception.