Ah, sorry, for some reason I thought the psi-weapon was not AoE and ignored that.
I do wonder how the original modder managed, but I guess lazy loading might have worked for them, too.
Thanks!
P.S. This error message might be improved a little, since as it is, I thought indexes had shifted, not that the image referenced by the index was not present at all. Something like 'missing image at index XYZ for ...' or similar?