Weird.. it worked before, but some update to another mod seems to have broken this one:

Mods to disable:Failed to load mods: Error while loading recipe prototype "se-arcosphere-fold-easy-a" (recipe): Key "icon" not found in property tree at ROOT.recipe.se-arcosphere-fold-easy-a.icons[1]
Modifications: Space Exploration Arcosphere Easy Folding
Mods to be disabled:
... arcosphere-easy-folding (0.0.1)

ok, they changed the icon names for arcospheres.

Where you previously had:
{ icon = a.icon, scale = 0.33, shift = {0, -16}, icon_size = 64 },

you need to change this to:
{ icon = a.icon_gfx, scale = 0.33, shift = {0, -16}, icon_size = 64 },
{ icon = a.icon_letter, scale = 0.33, shift = {0, -16}, icon_size = 64 },

(for all 6 entries in you data.lua)

I seem to have the same issue:
Failed to load mods: Error while loading recipe prototype "se-arcosphere-fold-easy-a" (recipe): Key "icon" not found in property tree at ROOT.recipe.se-arcosphere-fold-easy-a.icons[1]

I can confirm that Zarnoo's changes fix the error you get with this mod.