The following crashes: ```dafny class Dummy { const i: int constructor(i: int) { this.i := i; } } class ThisError { const d: Dummy const t: set<ThisError> := {this} constructor() { var x := set n: ThisError | n in t :: n.d.i; d := new Dummy(1); new; } } method Main() { var x := new ThisError(); } ```