Centroid returns nulls when passed a polygon denoting a point

[jezzalaycock]

For instance {
"type": "Polygon",
"coordinates": [
[
[
-112.03086,
33.653759
],
[
-112.03086,
33.653759
],
[
-112.03086,
33.653759
],
[
-112.03086,
33.653759
]
]
]
}

Returns {"type":"Point","coordinates":[null,null]}