Fix crash on player joining

init.lua

@@ -7,7 +7,7 @@ to this software to the public domain worldwide. This software is
 distributed without any warranty.
 ]]
 
-local MAX_INACTIVE_TIME = 300
+local MAX_INACTIVE_TIME = 20
 local CHECK_INTERVAL = 1
 local WARN_TIME = 20
 
@@ -36,6 +36,7 @@ minetest.register_globalstep(function(dtime)
 	--Loop through each player in players
 	for playerName,_ in pairs(players) do
 		local player = minetest.get_player_by_name(playerName)
+		if player then
 		
 			--Check for inactivity once every CHECK_INTERVAL seconds
 			checkTimer = checkTimer + dtime
@@ -63,4 +64,5 @@ minetest.register_globalstep(function(dtime)
 				end
 			end
 		end
+	end
 end)