JetPackParticleController not working in the 3D Platformet Tutorial

I'm going through the Unity 3D Platformer Tutorial, and the JetPackParticleController script doesn't work as intended. When I try to run the game I get the following errors:

 NullReferenceException: Object reference not set to an instance of an object JetPackParticleController+$Start$45+$.MoveNext () (at Assets/Scripts/Player/JetPackParticleController.js:23)
 NullReferenceException: Object reference not set to an instance of an object JetPackParticleController+$Start$45+$.MoveNext () (at Assets/Scripts/Player/JetPackParticleController.js:53)

I tried messing around with the script a bit but couldn't solve the problem. Help?