$client.credit_balance did not result in a number shown in email

I am trying to use the string $client.credit_balance in this simple message in the email body but it produced (as BCC’d to myself) this in the actual email:

image

Hi,

I don’t see that variable in the docs, you may want to create an issue on GitHub to request it.

Hello,

This variable is listed in the client section when customizing email templates:

In that case feel free to create an issue on GitHub to report it as a bug.