No Errata
Q: When I play Drifting Advance, do I have to push all friendly Chainrasps?
A: No (you can choose to push a Chainrasp 0 hexes, which is effectively the same as not pushing them). In addition, you cannot push a Chainrasp that is already adjacent to an enemy fighter, as they cannot be pushed closer to an enemy fighter (this doesn’t stop you playing the card, it simply means that it won’t affect that Chainrasp).
Q: Can I play Drifting Advance if there are no enemy fighters?
A: Yes. If you do, it will have no effect.