readableStream controller.error not calling cancel

repro-readablestream-controller-error.mjs

async function* makeGenerator() {
  try {
    let i = 0
    while (true) {
      yield i++
      await new Promise(r => setTimeout(r, 10))
    }
  } finally {
    console.log(">>> GENERATOR CLEANED UP (finally ran)")
  }
}

const iterable = makeGenerator()
const iterator = iterable[Symbol.asyncIterator]()

const stream = new ReadableStream({
  async pull(controller) {
    const { value } = await iterator.next()
    controller.enqueue(value)

    if (value === 3) {
      console.log(">>> ERRORING STREAM (controller.error)")
      controller.error(new Error("boom"))
      // NOTE: unless we do the below, generator finally does not run
      try { if (iterator.return) { await iterator.return() } } catch {}
    }
  },

  async cancel() {
    console.log(">>> STREAM CANCELED (cancel called)")
    if (iterator.return) {
      await iterator.return()
    }
  }
})

const reader = stream.getReader()

// consume until error
try {
  while (true) {
    const { value } = await reader.read()
    console.log("read:", value)
  }
} catch (e) {
  console.log("caught:", e.message)
}

// wait briefly so any finally could run if it were going to
await new Promise(r => setTimeout(r, 50))
console.log(">>> DONE")