[BUG]: `sortAxisCategoriesByValue` conditional doesn't handle `NaN` values

[camdecoster]

Description

The conditional check for sortAxisCategoriesByValue added in #7855 doesn't handle NaN values.

Steps to reproduce

• See this CI run

Notes

• I broke this when attempting to convert a confusing conditional check to a more explicit form
• This broke the test that was added in that PR, so good on the test ?

[camdecoster]

Closed by #7893.