There is currently an issue with the client due to the recent update, this could be causing that.
Also if "player" is null, this will cause you an issue:
Banks.GRAND_EXCHANGE.contains(player)
if (player != null && !myPlayer().isMoving()) {
if(Banks.GRAND_EXCHANGE.contains(player) ) {
player.interact("Trade with");
Sleep.sleepUntil(() -> getTrade().isCurrentlyTrading(), 10000);
}
}