Fatal error: exception "Assert_failure ownershipInference.ml:62:20"

[aigarashi]

input program:

/*type node = (int * node ref * node ref)  = mu1.(int, 1 ref, 1 ref) */

lonely_node(v){
  mkref (v, mkref null, mkref null)
}

connect(n1, n2){
  let (v1, prev1, next1) = *n1 in
  let (v2, prev2, next2) = *n2 in{
    next1 := n2;
    prev2 := n1;
  }  
}

{
  let n1 = lonely_node(1) in
  let n2 = lonely_node(2) in {
    connect(n1, n2)
  }
}

output:
Fatal error: exception "Assert_failure ownershipInference.ml:62:20"