Script continues to run after Destroy()?

I'm really confused. I simply wanted a script to destroy its parent (and itself), that's all. You can find the rest of my code here.

You can easily notice this part (I added parent here):

if not closeEnough then
    script.Parent:Destroy()
end

The problem is, it says that parent is nil. So I did this:

if not closeEnough then
    if script.Parent then script.Parent:Destroy() else script:Destroy() end
end

The results were slightly strange, so I added an error function:

if not closeEnough then
    if script.Parent then script.Parent:Destroy() else script:Destroy() end
    error("my life is a lie")
end

And guess what.

my life is a lie