Changes

function EnemyShipData:air_power()

function EnemyShipData:air_power()

     local air_power = 0

     local air_power = 0

     for i=1, self:slots() do

     for i=1, self:slots() or 0 do

         local slot_equipment, slot_space = self:slot(i)

         local slot_equipment, slot_space = self:slot(i)

         if slot_equipment == nil or slot_space == nil then

         if slot_equipment == nil or slot_space == nil then