Attempt to index nil with "FindFirstChild"?

I am making a localscript that is supposed to make the screen read on death, but when I try to check HealthChanged, it gives me this error.

Players.Uniplier.PlayerGui.Death.Death:3: attempt to index nil with 'FindFirstChild'

Here is my code.

local player = game:GetService("Players").LocalPlayer 
local char = player:FindFirstChild("Character")
char:FindFirstChild("Humanoid").HealthChanged:Connect(function()
	if char.charactervalues.Grabbed.Value == true then
		local death = script.Parent.Frame
		if char.Humanoid.Health <= 1 then
			death.Transparency = 0
		end
	end
end)