`controller.byobRequest` type incorrectly says value is possibly null while `autoAllocateChunkSize` is present.

🔎 Search Terms

autoAllocateChunkSize

🕗 Version & Regression Information

• This is the behaviour in every version I tried, and I reviewed the FAQ for entries about readable, streams, byob, and autoallocatechunksize

⏯ Playground Link

https://www.typescriptlang.org/play/?ts=6.0.0-dev.20250806#code/HYUw7gBASiCGAmsBGAbEBlALgJzgWwAoBvAKAgkwE8AHEALggCIlLMQBnRgGjIlgFdMAewCCKFEIDGsNgGEAFv2ABrdAEsAXvQgBGAAwAmACw9y1fuIKShwHEPEhsASgily5a7ez202AHSSEuwgBE4A3LweNnYO-ixCSDAAjvwcmH647NQ28AR64bwAvjyFBUA

💻 Code

new ReadableStream({
  type: "bytes",
  autoAllocateChunkSize: 1024,
  pull(controller) {
    controller.close();
    controller.byobRequest.respond(0);
  },
});

🙁 Actual behavior

TypeScript says controller.byobRequest can be ReadableStreamBYOBRequest | null and errors when one tries to do .respond on it as null doesn't have that.

🙂 Expected behavior

TypeScript should say controller.byobRequest is ReadableStreamBYOBRequest because the autoAllocateChunkSize property is set. Meaning it can't be null according to https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream/ReadableStream#autoallocatechunksize

Additional information about the issue

No response

提供された TypeScript Playground のリンクから始め、autoAllocateChunkSize と controller.byobRequest に関する ReadableStream コンストラクターの型定義を調べてください。nullability エラーを再現し、次に型定義が設定されたバイトストリームをどのように反映すべきかを判断し、例で nullability エラーなしに .respond(0) を受け入れられることを確認してください。