Ligo Test: `List.fold_right` returns the `Unbound primitive` error

ligo run test returns the unbound primitive error if run with List.fold_right.

Here is a minimal example, minimal_eg.mligo for which ligo run test minimal_eg.mligo returns unbound primitive.

let my_list : int list = [1; 2; 3]
let sum_right (i, acc : int * int) : int = acc + i


let test = 
  let sum_of_elements : int = List.fold_right sum_right my_list 0 in 
  sum_of_elements