[SOLVED]How do I make an animation play when I press a certain key?

I am a noob to scripting. I have been trying to assign an animation to play when I press an key. When I try this script it says "Players.starmelvin.PlayerScripts.LocalScript:8: attempt to index nil with 'Humanoid' ".

I searched it up and what I found kept saying that it means that the parent changed. I don't get how the parent changed and I need help. I am pretty trash at scripting so don't expect it to be really complicated.

Also keep in mind the child of the script is the animation and the animation id and stuff. Idk how to describe it. Basically I dragged the animation into the script. I think that means its a child.

local WaveAnimation = script.WaveAnimation
local UserInputService = game:GetService("UserInputService")

wait(1)

local player = game.Players.LocalPlayer
local char = player.Character
local hum = char.Humanoid

local WaveAnimationTrack = hum:LoadAnimation(WaveAnimation)

UserInputService.InputBegan:Connect(function(input,gameProccesedEvent)
	if input.KeyCode == Enum.KeyCode.F then
		wait(1.35)
		WaveAnimationTrack:Play()
	end
end)

Edit: Ok I have fixed the script based on a comment that I got which helped. But it appears it only works once. Right after I made the change and fixed it and then I tested the game it worked fine. But when I tried testing it again it stopped working and won't work again.