Modding Help Assets error in a mod that seems to work well

Hi, The error:

Code:

[Error] Could not load image asset '/weapons/sniperrifle/default', using placeholder default.
(AssetException) No such asset '/weapons/sniperrifle/default'

This is caused by a weapon mod, but as much as I look in the files I don't see anything missing, I think something is missing in the animation files maybe? not sure, in the game everything is fine, the weapons work as expected and look correct.

I could ignore the error because everything works, but I would prefer to know what causes the error and fix it, this error is repeated with many weapons in the mod, but they all work fine and as I said before, they all look good too, so I don't understand what causes the error.

Thanks!