Is your feature request related to a problem? Please describe.

A recent viz had some null titles -- would help to check validate somehow!

Describe the solution you'd like

Ex: https://gist.github.com/lmeyerov/423df6b3b5bd85d12fd74b85eca4a17a

• nodes not in edges
• edges referencing non-existent nodes
• na nodes/edges
• if colors/sizes/icons/titles, NA vals
• if no title and defaulting to guess title, NAs there