[Beginner] Rotation constraint with Limit

Hi, I'm new to scripting. I setup character and need my bone using rotation constraint with limitation.

Such as eyelid (follow eye's movement but not when it look upward)

Such as finger's root (rotate as finger bends, but not in reversed way as you can see in attached GIF)

I found someone's post, and it said;

So I set my variables,

But it happens to have error on minVal...

Since I'm new to script and rotation is much more complex than movement, I have no idea to proceed...

I really appreciate if someone could help me, thank you.