writer.fail(reason)

将写入器置于终端错误状态。如果写入器已关闭或出错，则此操作无效。与 write() 和 end() 不同，fail() 是无条件同步的，因为使写入器失败仅是一个纯状态转换，不涉及任何异步操作。

🌐 Put the writer into a terminal error state. If the writer is already closed or errored, this is a no-op. Unlike write() and end(), fail() is unconditionally synchronous because failing a writer is a pure state transition with no async work to perform.