Log malformed JWTs

What does this merge request do and why?

We are seeing errors due to JWTs not being parsed.

This commit logs these malformed tokens so we can investigate.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

Merge request checklist

• Tests added for new functionality. If not, please raise an issue to follow up.
• Documentation added/updated, if needed.

refs #400 (closed)