Interpolator throwing a NaN/undefined

Hey there,

First off, thank you for a wonderful library.
I encountered a bug when trying to interpolate two colors in Lch and okLch space. Everything works fine, except when an interpolated color is black or white and there are more than two colors to interpolate over.

In the example below, I've got 3 colors in the initial color array and something breaks. However, if I delete one of them and start just with two everything works fine.

If I inspect one of the missing colors I notice the CSS property: background: lch(73.90988017397126 107.41130153548478 **NaN**)
The NaN is probably generating the problem.

Code here: https://codesandbox.io/s/lch-interpolator-wt5yk5?file=/App.svelte

Also, if I put just black and white as starting colors I get background: lch(100.00000139649632 0 **undefined**) for white and lch(0 0 **undefined**) for black.

Does this happen because black and white being achromatic colors are missing the **h** attribute?