Liquid syntax error (line x): Expected id but found number

I was just working on one of my sites that has a data file and was getting an error:

Liquid syntax error (line xx): Expected id but found number

It took me a while to figure it out, my data file had numbers in the file name like 8x10-faqs.yml and that was the problem. Renamed it to just faqs.yml and it went away.

Even with the error it still built properly.

While trying to figure it out there was a promising link back to talk.jekyll but it was to the now gone old content. Posting again so maybe I will find it easier next time.

Jekyll v 3.3