-- ?T deref (WO-E213): reaching through a possibly-nil value without a nil
-- check. A field place never narrows — the fix is `let n = a.next; if n != nil`.
class Node {
  label: Text
  next: ?Node
}

fn main() -> Int {
  let a = Node { label: "a", next: nil };
  print(a.next.label);
  return 0
}