Pyramid.fromLayerRDD fails to respect NODATA values with ResampleMethods.Max

[CloudNiner]

I have a TileLayerRDD[SpatialKey] and am generating an image pyramid with the following code snippet:

def savePng(
    layer: TileLayerRDD[SpatialKey],
    colorMap: ColorMap,
    outputPath: String
  ): Unit = {
    implicit val sc: SparkContext = layer.sparkContext

    val (baseZoom, baseLayer) = layer.reproject(ZoomedLayoutScheme(WebMercator, 256))
    val pyramid = Pyramid.fromLayerRDD(
      baseLayer,
      Some(baseZoom),
      Some(0),
      resampleMethod = ResampleMethods.Max
    )

    pyramid.levels.foreach { case (zoom, tileRdd) =>
      val imageRdd: RDD[(SpatialKey, Array[Byte])] =
        tileRdd.mapValues(_.renderPng(colorMap).bytes)

      val keyToPath = { k: SpatialKey => s"${outputPath}/${zoom}/${k.col}/${k.row}.png" }
      if (outputPath.startsWith("s3")) {
        SaveToS3(imageRdd, keyToPath, { request =>
          request.toBuilder.acl(ObjectCannedACL.PUBLIC_READ).build()
        })
      } else {
        SaveToHadoop(imageRdd, keyToPath)
      }
    }
  }

When this layer is generated and displayed on a map, all zoom levels past the base zoom level replace nodata values with the value of the first color ramp:
https://tilejson.io/g/90e81c9fd2ed500609829d5df5af93dc/view

When I use the default ResampleMethod.Average this does not occur. It appears that MaxResample handles NoData values correctly

[CloudNiner]

Here's two images at approximately the same location that demonstrate the issue (if the tilejson link ever disappears):

No data filled in as we zoom out

Correct for basezoom

[echeipesh]

scala> val tile = ArrayTile.empty(DoubleConstantNoDataCellType, 4, 4)
tile: geotrellis.raster.MutableArrayTile = DoubleConstantNoDataArrayTile([D@708afe26,4,4)

scala> tile.asciiDrawDouble()
res13: String =
"    ND    ND    ND    ND
    ND    ND    ND    ND
    ND    ND    ND    ND
    ND    ND    ND    ND

"

scala> tile.resample(2, 2, ResampleMethods.Max).asciiDrawDouble()
res14: String =
" -2.147483648E9 -2.147483648E9
 -2.147483648E9 -2.147483648E9

"

Note, its important to use asciiDrawDouble because asciiDraw obscures the problem.

As @kervel pointed out on gitter:

    val doubleMax = indices.foldLeft(Double.MinValue) { case (currentMax, coords) =>
      val v = tile.getDouble(coords._1, coords._2)
      // Double.NaN would *always* be max
      if (isData(v)) math.max(currentMax, v) else currentMax
    }
    if (doubleMax == Double.MinValue) NODATA else doubleMax

here NODATA is the Int nodata... i think it should be doubleNODATA