[MattD]

There are a few problems here. It looks like the NullPointerException is from trying to feed the Watchdog incorrectly. "wd" is never assigned. Remove your Watchdog object and feed the Watchdog like this instead:

Watchdog.getInstance().feed();

The code in your operatorControl() method is only going to be called once. You need to place it in a loop, like this:

public void operatorControl()
{
    while (isEnabled() && isOperatorControl())
    {
        Watchdog.getInstance.feed();
        
         // operator control here
    }
}

You might also want to add in a small delay at the end of the loop body, since driver station input only comes in at 50Hz. There's not much of a point in reading input faster than that.