C# - 从 Amazon S3 存储桶下载文件，并在文件不存在时捕获错误

问：

我生成了一个需要从 S3 下载的文件名列表。一切正常，但是当它遇到不存在的文件时会中断。当我尝试列出存储桶的内容时，我收到一个拒绝访问错误，即使根据供应商的说法，这应该可以正常工作......所以我放弃了列出内容的尝试。

相反，有没有办法在异步方法尝试下载不存在的东西时捕获异步方法的错误而不会使我的程序崩溃？如果一个文件失败，我想移动到列表中的下一个文件。

当我尝试一个不存在的文件时出现的错误：

Amazon.S3.AmazonS3Exception: Access Denied --->   
Amazon.Runtime.Internal.HttpErrorResponseException: The remote server returned an error: (403) 
Forbidden. ---> System.Net.WebException: The remote server returned an error: (403) Forbidden. at 
System.Net.HttpWebRequest.GetResponse() at Amazon.Runtime.Internal.HttpRequest.GetResponse() --- 
End of inner exception stack trace 

我的代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.IO.Compression;
using Amazon;
using Amazon.S3;
using Amazon.S3.Model;
using Amazon.S3.IO;
using System.Threading;

namespace AlgoSeekDecompressor
{
    class Program
    {
        static void Main(string[] args)
        {
            var list = new List<string>()
            {
                "Apple.csv",
                "Banana.csv",
                "Canteloupe.csv",
            };

            var downloadPath = @"E:\My_Folder";

            Task.Run(async () => { await DownloadFilesAsync(list, downloadPath); }).Wait();

            Console.WriteLine("Done downloading");
        }

        static async Task DownloadFilesAsync(List<string> list, string downloadPath)
        {
            var accessKey = "#################";
            var secretAccessKey = "#########################";

            var client = new AmazonS3Client(
                accessKey,
                secretAccessKey,
                RegionEndpoint.USEast1
            );

            foreach (var file in list)
            {
                var bucketName = "amazon_s3_bucket";

                //There is a prefix that is the first letter of the filename
                var filename = file.Substring(0, 1).ToUpper() + "/" + file + ".csv.gz";

                var request = new GetObjectRequest()
                {
                    BucketName = bucketName,
                    Key = filename,
                    RequestPayer = RequestPayer.Requester
                };

                if (!Directory.Exists(downloadPath))
                {
                    Directory.CreateDirectory(downloadPath);
                    Console.WriteLine("Directory {0} does not exist - creating directory", downloadPath);
                }

                var filePath = Path.Combine(downloadPath, filename);
                var appendToFile = false;

                using (var response = await client.GetObjectAsync(request))
                {
                    await response.WriteResponseStreamToFileAsync(filePath, appendToFile, CancellationToken.None);
                }
            }
        }
    }
}