Anomaly when using CoInductive types

[euisuny]

Hello,

From Equations Require Import Equations.

CoInductive foo : Type := FOO1.

Equations ex (x: foo) : nat :=
  ex FOO1 := 2.

Error: Anomaly "Uncaught exception Not_found." Please report at http://coq.inria.fr/bugs/.

The above simple snippet throws an anomaly.
A normal Coq definition would work fine for the above example (as shown below), but it would be very nice if Equations had support for CoInductive types.

Definition ex (x: foo) : nat :=
  match x with FOO1 => 2 end.

Coq 8.14.1, coq-equations 1.3+8.14