Error Mod Vehicle

[JRVi]

https://mega.nz/folder/dCVhDL7A#NBIFweWDwXU7a6J56JL42g

This link contains an fbx and the complete prefab, which should I modify? what's wrong? What is missing for the vehicle to work?

I have followed the tutorials of the A17 and Lengthy Coughy vehicle template video without the expected result since this is the error that comes out in the Player-prev.log

NullReferenceException: Object reference not set to an instance of an object
  at EntityVehicle.Update () [0x00570] in <d885d5e5cbd941a78c268f40cc2ae744>:0 

NullReferenceException: Object reference not set to an instance of an object
  at EntityVehicle.CheckForOutOfWorld () [0x00171] in <d885d5e5cbd941a78c268f40cc2ae744>:0 
  at EntityVehicle.PhysicsFixedUpdate () [0x0032a] in <d885d5e5cbd941a78c268f40cc2ae744>:0 
  at EntityVehicle.FixedUpdate () [0x00000] in <d885d5e5cbd941a78c268f40cc2ae744>:0 

I would like to know where the error is.