Can someone explain or point out why this script crashes Roblox? [Sorry, it was just a silly error]

This script was literally working yesterday. Now every time the Player jumps off the seat it freezes and crashes Roblox. I get no errors, parenting is correct. There's no reason it should be acting like this.

seat = script.Parent
function onSitUp(child, Drift, EMP, GUI)
	if child.Parent == nil then
		Drift.Disabled = true
		EMP.Disabled = true
		Drift.Parent = script
		EMP.Parent = script
		GUI.Parent = script
	end
end

function onChildAdded(part)
			local char = script.Parent.Parent.Parent.Parent
			if char then
				local Drift = script["Drift"]
				local EMP = script["EMPscript"]
				Drift.Parent = char
				Drift.Disabled = false
				EMP.Parent = char
				EMP.Disabled = false
				local GUI = script["Controls"]
				local player = game.Players:GetPlayerFromCharacter(char)
				GUI.Parent = player.PlayerGui
				part.AncestryChanged:connect(function(child) onSitUp(child, EMP, GUI, Drift, script.Parent) end) 
			end
end

seat.ChildAdded:connect(onChildAdded)