Attempt to index nil with WaitForChild?

So here's my code. It's for a spawner.

-- Locals
local team = script.Parent:WaitForChild("Team").Value
local root = script.Parent.Location:WaitForChild("HumanoidRootPart")
local root2 = script.Parent.Parent.Spawn2.Location:WaitForChild("HumanoidRootPart")
local team1 = game:GetService("Teams"):WaitForChild("Assault")
local team2 = game:GetService("Teams"):WaitForChild("Defend")

-- Setup
for _, v in pairs(script.Parent:GetDescendants()) do
	if v:IsA("BasePart") then v.Anchored = true v.CanCollide = false end
end

for _, v in pairs(script.Parent.Location:GetDescendants()) do
	if v:IsA("BasePart") then
		v.Transparency = 1
		v.CanCollide = false
		v.Anchored = true
	end
end

-- Main
game:GetService("Players").PlayerAdded:Connect(function(plr)
	for i, v in pairs(game:GetService("Players"):GetChildren()) do
		if i < 1 then
			plr.Team = team1
		elseif i > 1 then
			plr.Team = team2
		end
	end	
	if plr.Team == team1 then
		plr.Character:WaitForChild("HumanoidRootPart").CFrame = root.CFrame
	elseif plr.Team == team2 then
		plr.Character:WaitForChild("HumanoidRootPart").CFrame = root2.CFrame
	end	
end) 

Please don't say "Use a spawnlocation" because i'm just testing this. So i keep getting this error: Workspace.Spawn.Script:31: attempt to index nil with 'WaitForChild'  -  Server  -  Script:31 How can i fix it?

I believe this means that the HumanoidRootPart is nil, and does not exist in plr.Character.

Wrap the if statement inside of a CharacterAdded event to avoid getting an error if the player's Character hasn't loaded yet.

I also recommend using the player's PrimaryPart instead of the HumanoidRootPart because of useful functions such as SetPrimaryPartCFrame. The player's primary part is always their HumanoidRootPart which works for R6 and R15.

plr.CharacterAdded:Connect(function(character)
	plr.Team == team1 then
		plr.Character:SetPrimaryPartCFrame(root.CFrame)
	elseif plr.Team == team2 then
		plr.Character:SetPrimaryPartCFrame(root2.CFrame)
	end
end