missing reference exception...and the noob

I have just started unity and i have no prior experience coding,and i am in other words the I’m a complete newbie and must learn everything so i got the fps tutorial and step by step added stuff but when finishing with the explosion script and connecting it to the rigid body missile and running the game i get this error

MissingReferenceException: The object of type ‘Rigidbody’ has been destroyed but you are still trying to access it.
Your script should either check if it is null or you should not destroy the object.
UnityEngine.Object.Internal_InstantiateSingle (UnityEngine.Object data, Vector3 pos, Quaternion rot) (at C:/BuildAgent/work/812c4f5049264fad/Runtime/ExportGenerated/Editor/UnityEngineObject.cs:44)
UnityEngine.Object.Instantiate (UnityEngine.Object original, Vector3 position, Quaternion rotation) (at C:/BuildAgent/work/812c4f5049264fad/Runtime/ExportGenerated/Editor/UnityEngineObject.cs:53)
pulse launcher.Update () (at Assets/weapon scripts/pulse launcher.js:7)

i dont know what this means and it is probably something super simple that I missed, but can some one please help a noob out

I just skimmed the error message, but looks like some bullet/rocket(whatever) gets destroyed, but some other script is still trying to look for it.

Can’t really help you out anymore without looking at script!

If the projectile is already in the scene, it will destroy itself at the first call to OnCollisionEnter(). If your launcher references this projectile instead of the prefab, it will then run into a MissingReferenceException. The same applies to the explosion.

I’m not sure whether OnCollisionEnter() is called if the script is disabled. If it isn’t, it would allow you to keep the projectile in the scene (if that is what you want/need?), if you make sure it is disabled until you launch it. Or use a “dead” projectile (one without the script) as a scene instance/representation.