Geometry causes "Unable to pop() SweepEvent" error to be thrown

[mfogel]

The performing a union() on the following polygons results in the library crashing with a "Unable to pop() SweepEvent ... from queue" error.

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": null,
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [-85.635, 34.546],
            [-85.64162299941661, 34.546027776790396],
            [-85.64157326850268, 34.53498609425157],
            [-85.635, 34.546]
          ]
        ]
      }
    },
    {
      "type": "Feature",
      "properties": null,
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [-85.644, 34.55],
            [-85.64162299941658, 34.54602777678346],
            [-85.64157326850268, 34.53498609425157],
            [-85.643, 34.54],
            [-85.635, 34.546],
            [-85.644, 34.55]
          ]
        ]
      }
    }
  ]
}

One of those polygons is a bit ugly in that it has a self-crossing ring, but polygon-clipping should be able to handle that just fine.