Allow for potentially empty tokens when creating CTA in program

I am creating an email chain in program that contains 3 emails followed by a call-to-action for the CSM if none of these emails were read. In order to make it easy for the CSM to act on these emails not read, I wanted to include in the Comments section tokens like the contact phone number which is not always filled.

The error "Token vakue is empty for placehorder 'Phone' at step Create CTA" for every contact that has no phone number defined. The creation of a CTA in program should allow for tokens that may be empty, much in the same way as we can do mailings with empty tokens. We don't necessarily need to set a default value. If empty, the token can just be skipped.