Shouldn't Gamepad.vibrationActuator be nullable?

[cdumez]

It is currently not marked as nullable in the Web DIL here:

• https://w3c.github.io/gamepad/extensions.html#partial-gamepad-interface

However, the specification for "Construction" seems to indicate it can be null:

Add new steps to a new Gamepad:

If gamepad has a vibration actuator that can play effects with type "dual-rumble", initialize gamepad's vibrationActuator attribute to a new GamepadHapticActuator with "dual-rumble". Otherwise, initialize gamepad's vibrationActuator attribute to null.

[cdumez]

cc @marcoscaceres