UnaryUnionOp throws NPE on [POINT EMPTY, LINESTRING(0 0, 1 1)]

[jagill]

When performing a union on an empty point with a linestring, UnaryUnionOp.union throws a NullPointerException. Code snippet at the bottom. The issue is:

1. union first performs a partial union for each geometry dimension (this leaves the arguments unchanged in this case) then performs the Linear and Planar geometry unions.
2. When it attempts to union the Puntal geometries with the Linear/Planar, it iterates through each point, getting its position.
3. But the position of an empty point is null, so when the envelope check is performed against the position, the p.x access throws an NPE.

This could be fixed by adding after PointGeometryUnion line 62

    Point point = (Point) pointGeom.getGeometryN(i);
    if (point.isEmpty()) continue;

Alternatively, the Envelope containment check could have a null guard, if we can assume that a null position is never contained in an Envelope.

Repro code snippet:

WKTReader reader = new WKTReader();
Geometry emptyPoint = reader.read("POINT EMPTY");
Geometry lineString = reader.read("LINESTRING (0 0, 1 1)");
Geometry union = UnaryUnionOp.union(ImmutableList.of(emptyPoint, lineString));  // NPE

[dr-jts]

What version are you using? I think this is fixed in master as of #484.

[jagill]

I'm using 1.16.1, which is the latest, I think? I'm glad this has already been fixed! What's the release schedule?

[jagill]

I've confirmed that current master fixes this problem. Thanks!