MissingComponentException: There is no ‘Camera’ attached to the “First Person Controller Prefab” game object, but a script is trying to access it.
You probably need to add a Camera to the game object “First Person Controller Prefab”. Or your script needs to check if the component is attached before using it.
FPSWalker.Start () (at Assets\Standard Assets\Scripts\FPSWalker.js:43)