hello! can you find whats wrong with my script? its a thing that kinda happens for some reason idk.

while true do
    wait(.5)
local Players = game:GetService("Players")
local player = Players.LocalPlayer
local character = player.Character
if not character or not character.Parent then
    character = player.CharacterAdded:wait()
end

if character.Humanoid.Health == 90 then
    script.Parent.Transparency = 0.9
    end



end

so thats the coodee, im trying to make a thing to become more transparent when the player's health gets over to 90. its showing an error on line 5 ("local character = player.Character ") the error just shows " attempt to index nil with 'Character' "