fix incomplete conversions

updatedshmup.p8

@@ -120,7 +120,6 @@ end
 function _init()
  init_bullet_mt()
  init_powerup_mt()
- init_ship_mt()
 	wipe_level()
 	primary_ship.main_gun = new_gun_of(zap_gun_t)
 	load_level(example_level)
@@ -939,7 +938,7 @@ end
 function spawn_rnd_x(typ)
  s = typ.new{
   x = rnd(104),
-  y = -(mt.__index.size * 8 - 1)
+  y = -(typ.size * 8 - 1)
  }
  eships:push_back(s)
  return s
@@ -951,10 +950,11 @@ function spawn_blocking_rnd_x(typ)
   x = rnd(104),
   y = -7,
   ice = 1,
+  orig_die = typ.die,
   die = function(self)
    freeze -= self.ice
    self.ice = 0
-   mt.__index.die(self)
+   self:orig_die()
   end
  }
  eships:push_back(s)