Add function args check to `redundant-existence-check`

[Anders Eknert]

fun(x) if {
    x
    # do more things
}

x can't be undefined in that location, as if it is, fun isn't going to be called in the first place. We should add this condition to the redundant-existence-check rule.

[Stephan Renatus]

fun(false) would make a difference, though. 🤔

[Anders Eknert]

Hmm, yeah, I guess you're right. We could recommend doing an explicit check for x == true I guess?
Or we could just leave it be.

[Stephan Renatus]

fun("whatever") would also work; so I guess the explicit check would need to be x != false.

Or we could just leave it be.

I'd be in favor of that. 😎

[Anders Eknert]

Hmm, surely "whatever" wouldn't pass as x == true? :)

But either way, I'll concede that this is probably better to leave as it is. One issue less to deal with 🙂