Empty objects are ignored by flatten

[vickyRathee]

I was using with paraparase and found that it ignores the empty object/array results in [object/object] in CSV download.

[
  {
    "token": "YCMG4IRRE6",
    "payment": {
      "currency": "USD",
      "amount": 10
    },
    "tracking": {}
  }
]

 const flattenned = data.map((d) =>
    flatten(d)
  );
  return Papa.unparse(flattenned);