How can I get a PixelsObject from a Texture in Incisor?

I’m following the Incisor API documentation to create a PixelsObject from a graphic. I’ve confirmed that pawn.png is in my Assets directory and visible in LiveView. However, I’m getting an exception on the second line of code, and the console log is never displayed.

Here’s a simple block of code that will reproduce the error:

class ProjectMain {
    init() {
        let pawn = new GraphicObject(nc.graphicAssets.pawn, nc.mainScene, "Pawn");
        let pawnPixelsObject = nc.pixelsObjects.getPixelsObject(pawn.materialMaster.mainTexture);
        console.log(pawnPixelsObject);
    }
}

Can anyone help me understand why an exception occurs?