fix pandorabox-io/pandorabox.io#392

an additional fix is needed for the replacer to place cable plates correctly: https://github.com/pandorabox-io/pandorabox.io/issues/392#issuecomment-569590793

technic/machines/register/cables.lua

@@ -241,6 +241,7 @@ function technic.register_cable(tier, size)
 						num = xyz[((fine_pointed[bigger] < 0 and "-") or "") .. bigger]
 					end
 				end
+				if num == nil then num = 1 end
 				return item_place_override_node(
 					itemstack, placer, pointed_thing,
 					{name = "technic:"..ltier.."_cable_plate_"..num}