Mach aus der lokalen variable einen skill und nimm eine seperate funktion (s.o.) zum ändern des skill wertes.
Code:

---

define lights, skill40;

action player_move
{
  player = my;
  my.lights = 0;
  ...
}

function switch_PlayerLights()
{
  //check if player entity exists
  if(player)
  {
    //switch the lights skill
    player.lights = !player.lights;
  }
}

on_t = switch_PlayerLights;

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