an effort at a minimal example of the Cannot read property '0' of null in clipCells() error message described in d3-voronoi github issue 16
this example renders the Voronoi example as expected, and does not reproduce the error.
strangely, when I pass the same data to d3.voronoi() inside my larger app elsewhere, I experience the error.
the code for the d3-voronoi-scatterplot chart plugin is at https://github.com/micahstubbs/d3-voronoi-scatterplot