ValidationError: for loop body must terminate with a yield or return when verifying the following statement `scf.For`

[jon-wurtz]

When running the following example script

@move
def foo_move():
    init.fill([spec.get_static_trap(zone_id="traps")])
    for _ in range(3):
        zone = spec.get_static_trap(zone_id="traps")
        src = grid.sub_grid(zone, [-1], [3])
        dst = grid.sub_grid(zone, [15], [7])
        waypoints = ilist.IList([src, dst])
        move_by_waypoints(waypoints, True, True)

This raises an error

ValidationError: for loop body must terminate with a yield or return when verifying the following statement  `scf.For` at
     scf.for %_ in %5 {
           %zone = qourier.spec.get_static_trap(){zone_id='traps' : !py.str} : !py.Grid[!Any, !Any]
              %7 = py.constant.constant 1 : !py.int
              %8 = py.unary.usub(%7) : ~T
              %9 = py.ilist.new(values=(%8)){elem_type=~T} : !py.IList[~T, Literal(1,int)]
             %10 = py.constant.constant 3 : !py.int
             %11 = py.ilist.new(values=(%10)){elem_type=!py.int} : !py.IList[!py.int, Literal(1,int)]
            %src = grid.get_sub_grid(zone=%zone, x_indices=%9, y_indices=%11) : !py.Grid[~GetNumX, ~GetNumY]
             %12 = py.constant.constant 15 : !py.int
             %13 = py.ilist.new(values=(%12)){elem_type=!py.int} : !py.IList[!py.int, Literal(1,int)]
             %14 = py.constant.constant 7 : !py.int
             %15 = py.ilist.new(values=(%14)){elem_type=!py.int} : !py.IList[!py.int, Literal(1,int)]
            %dst = grid.get_sub_grid(zone=%zone, x_indices=%13, y_indices=%15) : !py.Grid[~GetNumX, ~GetNumY]
      %waypoints = py.ilist.new(values=(%src, %dst)){elem_type=!py.Grid[~GetNumX, ~GetNumY]} : !py.IList[!py.Grid[~GetNumX, ~GetNumY], Literal(2,int)]
             %16 = py.constant.constant True : !py.bool
             %17 = func.invoke move_by_waypoints(%waypoints, %16, %16) : !py.NoneType maybe_pure=False
    } -> purity=False

Source Traceback:
  File "/Users/jwurtz/Documents/Python/aist_hypercube_moves.py", line 104, col 43
     │  dst = grid.sub_grid(zone, [15], [7])
     │  waypoints = ilist.IList()
  104│  move_by_waypoints(waypoints, True, True)

Note that if the waypoint calculations are put outside the loop, there is no error

@move
def foo_move():
    init.fill([spec.get_static_trap(zone_id="traps")])
    zone = spec.get_static_trap(zone_id="traps")
    src = grid.sub_grid(zone, [-1], [3])
    dst = grid.sub_grid(zone, [15], [7])
    waypoints = ilist.IList([src, dst])
    for _ in range(3):
        move_by_waypoints(waypoints, True, True)