val content = object : OutgoingContent.WriteChannelContent() {
    override suspend fun writeTo(channel: ByteWriteChannel) {
        val stream = channel.toOutputStream()
        try {
            withContext(Dispatchers.IO) {
                stream.run {
                    write(1)
                    write(2)
                    flush()
                    TODO("oops!")
                }
            }
        } catch (e: Throwable) {
            channel.close(e)
            throw e
        } finally {
            channel.close()
        }
    }
}
context.respond(content)