Convert NODATA ByteConstantTile and ShortConstantCellType: unexpected result

[bossie]

Describe the bug

A NODATA ByteConstantTile that is converted to its own CellType, is no longer NODATA.

To Reproduce

import geotrellis.raster.{ByteConstantTile, byteNODATA}

val t = ByteConstantTile(byteNODATA, cols = 1, rows = 1)
assert(t.isNoDataTile)
assert(t.convert(t.cellType).isNoDataTile) // boom

Expected behavior

Seeing as the CellType doesn't change, this should be a no-op and the tile should remain NODATA.

Screenshots

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Environment

• Java version: openjdk version "1.8.0_382"
• Scala version: 2.12.15
• GeoTrellis version: 3.6.0

Additional context

Add any other context about the problem here.

[pomadchin]

Thanks for reporting!

There is a bug in the NoData conversion. 👍 nice catch; wondering if any other cellTypes might be affected.

[moradology]

Looked into this a small amount yesterday and it appears to be related to NoData in particular, so I'd guess this can happen in other contexts. Going to see about addressing this today

[jdries]

@moradology I did a quick PR, I can expand it a bit further if you believe this general direction is fine.
We'd like to solve this one as it's a fairly important issue for correctness.