instance_exists failure

if (array_length_1d(projectiles) > 0) {
    for (var i = 0; i < array_length_1d(projectiles); i++) {
        if (projectiles[i] != noone)) {
            if (projectiles[i][? "length"] > 0
                && instance_exists(projectiles[i][? "id"]) ) {

                projectiles[i][? "length"] -= 1;

                var total_life = variable_instance_get(projectiles[i][? "id"], "length");
                variable_instance_set(projectiles[i][? "id"], "hsp",
                    ease_cubeIn(
                        0,
                        floor(10 * projectiles[i][? "ratiox"]),
                        total_life - projectiles[i][? "length"],
                        total_life
                    )
                )
            } else {
                ds_map_destroy(projectiles[i]);
                projectiles[i] = noone;
            }
        }
    }
}