Good One! There are two issues here:

1. Tuple or Array? The inferred type will be different depending on that decision.

Currently, I go for the Array one, so if you remove the `a[0].length` line, you will see `a` be inferred as `[string|number]`. But this will change if I think about this more thoroughly. What are your thoughts?

2. const/let constrain, constexpr, `if guarding,` and some internal methods are not implemented yet, so this is a false negative. But indeed will do!