NLog写入AzureBlobStorage异常：单条日志超638字符生成空文件

问题现象 #

• 使用包版本：NLog.Extensions.AzureBlobStorage 4.2.0
• 当日志消息长度不超过638字符时，写入Azure Blob Storage功能正常
• 消息长度超过638字符（例如639个"a"组成的字符串）时，会生成空文件，甚至超长日志之前的消息也不会被记录
• 将消息缩短至368字符时，功能恢复正常

复现代码 #

var config = new LoggingConfiguration();
var blobStorageTarget = new BlobStorageTarget
{
    Name = blobStorageTargetName,
    ConnectionString = "<my connection string>",
    Container = "myContainer",
    BlobName = $"{prefix}_YourBlobName_${{shortdate}}.log",
    Layout = "${longdate} ${level} ${message}"
};
config.AddTarget(blobStorageTarget);
var rule = new LoggingRule("*", LogLevel.Trace, blobStorageTarget);
config.LoggingRules.Add(rule);
LogManager.Configuration = config;
var logger = LogManager.GetCurrentClassLogger();

logger.Error("now we will soon log the longer String");
string myString = string.Concat(Enumerable.Range(0, 639).Select(i => "a"));

logger.Error(myString);

logger.Trace($"Trace msg at {DateTime.UtcNow:O}");
logger.Debug($"Debug msg at {DateTime.UtcNow:O}");
logger.Info($"Info msg at {DateTime.UtcNow:O}");
logger.Warn($"Warn msg at {DateTime.UtcNow:O}");
logger.Error($"Error msg at {DateTime.UtcNow:O}");

LogManager.Flush();

背景 #

此问题为同一异常的后续提问，此前已提交相关问题。

内容的提问来源于stack exchange，提问作者Sebastian