SolidPolygonLayer fails when passing a luma `Buffer` for getPolygon: `Error: cannot read geometries`

Description

I have a composite layer whose renderLayers method is being implemented like this (as a contrived example):

  renderLayers(): SolidPolygonLayer<D>[] {
    const { gl } = this.context;

    const positions = new Float32Array(
      [
        [400, 400, 500, 400, 500, 500, 400, 500, 400, 400],
        [600, 600, 700, 600, 700, 700, 600, 700, 600, 600],
        [800, 800, 900, 800, 900, 900, 800, 900, 800, 800],
      ].flat()
    );
    const startIndices = new Uint16Array([0, 5, 10]);

    const buffer = new Buffer(gl, positions);
    const getPolygon = { buffer, offset: 0, size: 2, type: GL.FLOAT };

    return [
      new SolidPolygonLayer(
        this.getSubLayerProps<D>({
          _normalize: false,
          data: {
            attributes: {
              getPolygon,
            },
            length: 3,
            startIndices,
          },
          getFillColor: [0, 100, 60, 160],
          id: "test-layer",
        })
      ),
    ];
  }

Instead of rendering the polygons, I get this error (full trace below):

Error: cannot read geometries

If I just change this:

    const buffer = new Buffer(gl, positions);
    const getPolygon = { buffer, offset: 0, size: 2, type: GL.FLOAT };

to this:

    const getPolygon = { size: 2, value: positions };

everything works!

The reason that I am expecting this to work with a Buffer is because that is what is demonstrated in this example:
https://github.com/visgl/deck.gl/blob/master/examples/experimental/interleaved-buffer/app.js

Expected Behavior

The data should render, regardless of whether it is passed as a typed array or as a luma buffer.

Repro Steps

I can provide a working demo if necessary.

Environment

• Framework Version: deck.gl 8.4.11
• Browser Version: Chrome 95.0.4638.69
• OS: Mac OS X 11.6.1

Logs

Error: cannot read geometries
    at Object.assert [as default] (assert.js:6)
    at PolygonTesselator2.getGeometryFromBuffer (tesselator.js:106)
    at PolygonTesselator2.getGeometryFromBuffer (polygon-tesselator.js:99)
    at PolygonTesselator2.updateGeometry (tesselator.js:66)
    at PolygonTesselator2.updateGeometry (polygon-tesselator.js:57)
    at SolidPolygonLayer2.updateGeometry (solid-polygon-layer.js:293)
    at SolidPolygonLayer2.updateState (solid-polygon-layer.js:262)
    at SolidPolygonLayer2._updateState (layer.js:670)
    at SolidPolygonLayer2._initialize (layer.js:635)

Start with the geometry-reading path in tesselator.js and polygon-tesselator.js, then inspect how SolidPolygonLayer.updateGeometry in solid-polygon-layer.js handles typed arrays versus luma Buffers. Reproduce the supplied example and verify that the Buffer form renders the same polygons without the “cannot read geometries” error.