Error of exactly zero will trigger SVD failure when generating absolute values

[IAlibay]

If you somehow have an error of zero in your input to cinnabar, and then call generate_absolute_values, you'll end up with an SVD failure in np.linalg.pinv (alongside a bunch of NaN's along the way).

We should capture this edge case and ensure that folks don't feed in such values, or at least pad the number by a tiny value.