attempt to index nil with 'WaitForChild'?

I'm making a death animations script and upon testing, the error

Workspace.Character.DeathAnims:4:attempt to index nil with 'WaitForChild'

appears in the output

local char = script.Parent
local hum = char:WaitForChild("Humanoid")
local backUpChar = char:Clone()
backUpChar:WaitForChild("DeathAnims"):Destroy()

hum.Died:Connect(function()
	local deathPos = char.HumanoidRootPart.Position
	local deathOri = char.HumanoidRootPart.Orientation
	local bac = backUpChar:Clone()
	local destme = char
	script.Parent = bac.Humanoid
	destme:Destroy()
	bac.Parent = workspace
	bac.HumanoidRootPart.Position = deathPos
	bac.HumanoidRootPart.Orientation = deathOri
	bac:MakeJoints()
	hum = bac.Humanoid
	hum.HealthDisplayDistance = 0
	hum.MaxHealth = math.huge
	hum.Health = math.huge
	local death_Anim = Instance.new("Animation")
	death_Anim.AnimationId = 'rbxassetid://4643698669'
	local track = hum:LoadAnimation(death_Anim)
	--script.Parent.Parent.HumanoidRootPart.Anchored = true
	track.Priority = Enum.AnimationPriority.Action
	track:Play()
	wait(0.66)
	hum.Health = 0
	script:Destroy()
end)

I recommend using Find First Child

	backUpChar:FindFirstChild("DeathAnims"):Destroy()

I have had this same type of problem, I did some research and found out that "WaitForChild()" has a "TimeOut" feature meaning you can set how long you want is to wait for:

the "10" represents however long you want it

WaitForChild("Name To Search For", 10)