Third Person Controller error

Hi guys. I am new to unity. Whenever I press the play button, it comes up with this error:NullReferenceException
ThirdPersonController.Update () (at Assets/Standard Assets/Character Controllers/Sources/Scripts/ThirdPersonController.js:350). If someone could help then that would be great.

A. Double-click the error message, and MonoDevelop should open at line 350 of the script ThirdPersonController.js. That line for me looks like:

_animation[walkAnimation.name].speed = Mathf.Clamp(controller.velocity.magnitude, 0.0, walkMaxAnimationSpeed);

B. A NullReferenceException means some script is trying to access some object but that doesn’t exist. Some scripting experience tells me that your problem is likely to be that the walkAnimation or controller objects are not set to a value. So, search for those in the code.

C. walkAnimation appears at line 7. This is probably set to a value in the inspector, so make sure you’ve dragged and dropped an animation clip onto this slot.

D. controller appears all over the place, so if there was a problem with this, you’d get more errors. So (C) is likely to be the problem.