SEOmatic Errors in Debug - Can they be fixed?
These errors will only appear with devMode on, and they are intended to help you diagnose potential problems with the meta tags and other information that you are rendering.

These are all soft errors, though. You can safely ignore them if they are a result of you not filling in things that you don't intend to fill in. 

You can read more about it here: https://github.com/nystudio107/craft-seomatic#meta-object-validation