服务器发生错误时所提供的唯一错误码，打印在 Proxy 后端或 JDBC 启动日志中。

错误码	错误信息
SPI-00001	No implementation class load from SPI ‘%s’ with type ‘%s’.
PROPS-00001	Properties convert failed, details are: %s.
PROXY-00001	Load database server info failed.