writer[Symbol.asyncDispose]()

如果写入器是打开的，调用 writer.fail()。如果写入器在 end() 或 endSync() 之后关闭，等待缓冲数据排空。如果写入器已经关闭或出错，则立即完成。

🌐 If the writer is open, calls writer.fail(). If the writer is closing after end() or endSync(), waits for buffered data to drain. If the writer is already closed or errored, resolves immediately.