Possible bug in my ES256 Signature code

Dear Credentials,

I'm struggling with getting the correct signature for ES256 with a JWT.

Here is Example that I am following:
https://www.rfc-editor.org/rfc/rfc7515#appendix-A.3

Here is the Code that I have:
https://gist.github.com/bshambaugh/427bb7e41fbe3f0169745fd3e821c2a5

If you discover anything I am overlooking, please let me know.

Thanks,

Brent Shambaugh