在 Client#parser_execute 中出现 NoMethodError，当读取缓冲区仅包含 CRLF（纯 `\r\n\r\n` 请求）时

The rescue block in Puma::Client#parser_execute that enriches HttpParserError messages raises NoMethodError: undefined method 'split' for nil when the read buffer contains nothing but CRLFs — for example when a client sends a bare \r\n\r\n.

https://GitHub.com/puma/puma/blob/master/lib/puma/client.rb#L314-L315