This issue should be resolved with macOS Ventura 13.2
Answer from Ezekiel on Stack ExchangeApple ID “(null)” and unable to sign-out - Apple Community
icloud - Apple ID on System Settings asking for «the password for the Apple ID "(null)"» for ever, how to solve? - Ask Different
What does password for (null) mean? I’ve tried entering my
null - Apple Community
This issue should be resolved with macOS Ventura 13.2
I've had a similar problem with a client using an earlier operating system. We had to resort to Apple Tech Support on a telephone call.
Now that you've updated to the most recent operating system, I suggest signing out of your Apple ID and then signing in again. To do this, in System Settings tap your name. Scroll to the bottom of the pane and click Sign Out.
Note: if you use iCloud Drive for storage, or Mail, Contacts, Calendars, etc. you will be asked what you want to do with that data before logging out. Here's more info.
https://support.apple.com/guide/mac-help/sign-apple-settings-mac-mh36825/13.0/mac/13.0
If that doesn't clear the error, I would suggest calling Apple Support. They will connect you with the team that specializes in Apple ID. The geniuses at the stores are not allowed to do Apple ID stuff, so I'd start with a call.
Has anybody gotten (null)-(null) error when trying to add Apple card to wallet?