lalals.cs

       public async Task InvokeAsync(HttpContext httpContext)
        {
            httpContext.Response.ContentType = "application/json";
            httpContext.Response.StatusCode = 200;
            try
            {
            
                await _next(httpContext);

            }
            catch (InternalException.Error em)
            {
                await httpContext.Response.WriteAsync(ExceptionToString(em));
            }

        }

        private string ExceptionToString(InternalException.Error exp)
        {
            var reply = new
            {
                isError = true,
                code = exp.ErrorCode,
                message = exp.ErrorMessage

            };
            return JsonConvert.SerializeObject(reply);
        }