js - array .reduce returns NaN instead of calculated value

I am writing a simple reduce function:

var tiles = [
  {
    "date": "2017-11-26",
    "cloudCoverage": 92.2,
    "area": 12055600804
  },
  {
    "date": "2017-11-26",
    "cloudCoverage": 92.78,
    "area": 12055600804
  },
  {
    "date": "2017-11-26",
    "cloudCoverage": 97.29,
    "area": 11609327018
  }
]

function selectDateTile(tiles) {
  return tiles.reduce((tile, currentPick) => {
    console.log('tileArea: ', tile.area, 'currentPick area: ', currentPick.area)
    return tile.area + currentPick.area
  });
}

console.log(selectDateTile(tiles))

I would expect it to log the actual values of the objects, and the sum of all the areas:

"tileArea: " 12055600804 "currentPick area: " 12055600804 "tileArea: " 12055600804 "currentPick area: " 24111201608 ...

But the console output I am getting in jsbin is:

"tileArea: " 12055600804 "currentPick area: " 12055600804 "tileArea: " undefined "currentPick area: " 11609327018 NaN

What am I doing wrong?

jsbin reference