original.name="Coercion_Invalid_2"
======
>>> main.whiley
type List1 is {null | List1 next, int | null data}

type List2 is {null | List2 next, int data}

type List3 is {null | List3 next, null data}

type List4 is List3 | List2

function f(List1 r) -> List4:
    return r

---
E400 main.whiley 10,11