找出哪个firestore批处理操作失败,以及哪些数据写入了数据库?

try {
  const characterPrivateRef = firestore().doc(`characters/${uid}`);
  const usernameRef = firestore().doc(`usernames/${username}`);
  firestore().batch().batch.create(characterRef, {...characterData});
  firestore().batch().batch.create(characterPrivateRef, {...usernameData});

  await firestore().batch().commit();
  // How can I get data written to each firestore document from batch 
  here?
} catch (e) {

  // How can I check what batch failed here i.e. if it was username I 
  want to show error saying something like ("Username already exists")
}