Fix shutdown on player leave/cozylights

mods/cozylights/init.lua

@@ -562,6 +562,7 @@ minetest.register_globalstep(function(dtime)
 		for _,cozyplayer in pairs(cozylights.cozyplayers) do
 			local t = os.clock()
 			local player = minetest.get_player_by_name(cozyplayer.name)
+			if not player == nil then 
 				local pos = vector.round(player:getpos())
 				pos.y = pos.y + 1
 				local wield_name = player:get_wielded_item():get_name()
@@ -571,6 +572,7 @@ minetest.register_globalstep(function(dtime)
 				end
 			end
 		end
+	end
 
 	on_gen_dtime = on_gen_dtime + dtime
 	if on_gen_dtime > on_gen_step then