How to patch a field of an object in an array using the Sanity JavaScript client

{
    "_id": 'aFuiYGWUw0SSAvMnYQafry',
    "entries": [
        {
            "_key": "BjDASDLOMkBsqk1tqRecKu"
            ...other keys and values
        },
        {
            "_key": "E0vulMwINU3H9ETBqXnRT7",
            ..oher keys and values
            "subentries": [
                {
                    "data": "saved datas",
                    "_key": "6b8c867d-36b9-4eff-97e0-9fd5be6c6ee4"
                },
                => insert data here
            ]
        }
    ]
}

{ "set": { "body[_type==\"cta\"].text": "Do the thing!" } }

{
  "mutations": [
    {
      "patch": {
        "id": "aFuiYGWUw0SSAvMnYQafry",
        "set": {
          "entries"[_key==\"E0vulMwINU3H9ETBqXnRT7\"] : {
            "insert": {
              "after": "subentries[-1]",
              "items": ["=> insert data here"]
            }
          }
        }
      }
    }
  ]
}

writeClient.patch(<documentID>)
        .setIfMissing({
            [`entries[_key==\"${entryId}\"].subentries`]: []
        })
        .append(`entries[_key==\"${entryId}\"].subentries`, [{
            _key: uuid(),
            ...=> data here
        }])
        .commit()