stream/iter: fromWritable().writev() leaves Writable corked when chunk validation throws #63294

Version

26.1.0

Platform

macOS 26.5.0

Subsystem

stream

What steps will reproduce the bug?

import { strictEqual, throws } from "node:assert";
import { Writable } from "node:stream";
import { fromWritable } from "node:stream/iter";

const writable = new Writable({
  write(chunk, enc, cb) {
    cb();
  },
});

const writer = fromWritable(writable);

throws(() => writer.writev([new Uint8Array([1]), 42]), {
  code: "ERR_INVALID_ARG_TYPE",
});

// Expected: writev() should uncork even when a later chunk conversion throws.
strictEqual(writable.writableCorked, 0);

Run with

node --experimental-stream-iter repro.js

How often does it reproduce? Is there a required condition?

Always

What is the expected behavior? Why is that the expected behavior?

fromWritable().writev() should either complete the batched write or throw/reject without changing the underlying Writable’s corking state. If writev() internally calls writable.cork(), it should always pair that with writable.uncork(), including when converting or validating a later chunk throws.

What do you see instead?

Calling writer.writev([new Uint8Array([1]), 42]) throws ERR_INVALID_ARG_TYPE, but the wrapped classic Writable remains corked afterward (writable.writableCorked === 1). This happens because writev() corks before converting all chunks, and if toUint8Array() throws for a later chunk, the uncork() call is skipped.

Additional information

No response