Am I using the .Character command correctly?

I am working on a local script that detects the team a player is on and changes their team if they die.

while true do
	local t1 = game.Teams:WaitForChild("T1")
	local t2 = game.Teams.T2
	local t3 = game.Teams.T3
	local t4 = game.Teams.T4
	local tu = game.Teams.Undescided
	local player = game.Players.LocalPlayer	
	local plr = player.Character.Humanoid
	plr.Died:Connect(function()
		if player.Team == t1 or player.Team == t2 or player.Team == t3 or player.Team == t4 then
			player.Team = tu					
		end
	end)
	wait(.5)
end

The error is on line 8 saying " ReplicatedFirst.DeathScript:8: attempt to index field 'Character' (a nil value)" I'm pretty sure that I've used the LocalPlayer.Character before in a local script, but for some reason this one isn't working correctly. I'm sure this is something that I have set up wrong but I would love some help getting it to work. (This is a local script in the ReplicatedFirst folder) Let me know if you need any more information! Thank you!

Its because your script runs before the character has time to load into the workspace, just use a Wait() method to make sure the character loads before assinging the variable

local plr = game.Players.LocalPlayer.CharacterAdded:Wait()

I'd recommend doing this on the server. Staying true to your version, try this.

local Teams = game:GetService('Teams')
local Players = game:GetService('Players')

local Player = Players.LocalPlayer
local Character = Player.CharacterAdded:Wait()
local Humanoid = Character:WaitForChild('Humanoid')

local Team1 = Teams:WaitForChild('T1')
local Team2 = Teams:WaitForChild('T2')
local Team3 = Teams:WaitForChild('T3')
local Team4 = Teams:WaitForChild('T4')
local Undecided = Teams:WaitForChild('Undescided')

Humanoid.Died:Connect(function()
	if Player.Team ~= Undecided then
		Player.Team = Undecided                    
	end
end)