The short answer is that the SVGShape doesn’t support clipPath and is incorrectly drawing what’s in the <def> section. If you remove the <path> from within clipPath, the black box goes away.
I added axis at origin, changed background to white and removed centering so its easier to see
I’ll make a few corrections and post an update tomorrow.
Note that SVGShape doesn’t support clipPath. I’ll update readme with SVG elements not supported.