Failed to load mods: The given sprite rectangle (left_top=0x0, right_bottom=120x120) is outside the actual sprite size (left_top=0x0, right_bottom=120x64).
If this is being used as an icon you may need to define the icon_size property.
See the log file for more information.: base/graphics/icons/gun-turret.png

Factorio 2.0.72

What other mods do you have enabled? Because I don't get this error while loading just Howitzer.

I'll see if I can isolate what it is. My guess was the Space Age HD textures packs, but I'll see if I can figure it out.

Found it, it conflicts with this one:
https://mods.factorio.com/mod/achievements_plus_plus_plus_plus

My guess is that when it pops up to show you the achievement, it wants an icon in the right size.

Oh strange, I'll look into it.