I keep getting this error on startup:
Failed to load mods: Error while loading entity prototype "atomic-artillery-projectile" (artillery projectile) : Unknown trigger effect item type: invoke tile trigger

Any way to fix this?

... what version of the game are you using?

The Atomic Artillery is a new weapon I added to the game in the previous update, if it's not working with your version of the game, you could always just revert to the previous version, however...

when I made the artillery, I just copied the existing rocket launched atomic bomb, and edited it to work with artillery.
From what I recall, they added new effects to destroy the decoratives with such things. I didn't think of it at the time when I released the mod, but it could be that it only works with the very latest version of the game. (0.18.22 at the time of writing)