How can I fix this block of code from freezing the game? (easy for experienced)

I'm extremely new to scripting. I've been messing around and challenging myself to script certain stuff. Below is the code block, and I've commented on the block that freezes the game.

It's also an edited version of the fire tutorial on the wiki.

wait(1) -- Waits for player to load in.

-- Variables for the lava, users, user HP, and checking to see if player has touched lava.
local Lava = game.Workspace.Lava1
local user = game.Players.LocalPlayer.Character.Humanoid
local userHP = game.Players.LocalPlayer.Character.Humanoid.Health
local userOnFire = Lava.Touched


-- Function that creates the fire effect.
function lightOnFire(part)
    print("Going to light this part on fire:")
    print(part.Name)

    local fire = Instance.new("Fire")
    fire.Parent = part
end

userOnFire:connect(lightOnFire) --calls upon function




-- The below code is freezing the game when I attempt to load in.
if userOnFire then
    repeat
        user:TakeDamage(5)
    until 
        userHP <= 0
    else 
        print("I am not on fire!") -- Even without this line, the game freezes.
end