What is this MakeOTF error all about?

OT features have been working fine for several months. Now I was just batch editing (without changing anything in the features) and noticed this error. I have an older version with exactly the same code and it works perfectly fine.

How can I fix this?

Also if I copy the code from the older version (that works fine), into this one, I still get this error. If I delete this bit where the “error” is everything’s error free.

Could be anything, also immediately before the indicated word. Possibly an invisible character?

Thanks @mekkablue . That’s it… an invisible character. I must have deleted the "s.beg_caron " (which was before the “s.beg_commaccent”) without noticing.