Attempt to index upvalue 'char' (a nil value)?

So, I've been experimenting a lot with KeyPressing as well as animation and it has been working out (in studio only). I would look for errors in the local logs in the actual game and would get "Attempt to index upvalue 'char' (a nil value)".

So here's the code:

local Player = script.Parent.Parent
local mouse = Player:GetMouse()
local char = Player.Character


function onKeyDown(key)
    key = key:lower()
    if key == "r" then
--------------------------------------------------------------------------      
            local animation = Instance.new("Animation")
animation.AnimationId = "http://www.roblox.com/Asset?ID=676773078"

char.Humanoid.WalkSpeed = 0     

local animTrack = char.Humanoid:LoadAnimation(animation)

wait(0.5)
animTrack:Play()
---------------------------------------------------------------------------


        wait(2.5)
char.Humanoid.WalkSpeed = 16

end
    end
mouse.KeyDown:connect(onKeyDown)

Now, this is in a LocalScript which apparently brings more complications like being unable to run things globally? Like, if I changed local char to just char, it doesn't tag char because it's global? I don't know, I'm not very adept at this.