Missing Field Exception

This line of javascript code:

collider.enabled = false;

is producing this exception:

MissingFieldException: Field 'UnityEngine.SphereCollider.enabled' not found.
Boo.Lang.Runtime.DynamicDispatching.PropertyDispatcherFactory.FindExtension (IEnumerable`1 candidates)
Boo.Lang.Runtime.DynamicDispatching.PropertyDispatcherFactory.Create (SetOrGet gos)
Boo.Lang.Runtime.DynamicDispatching.PropertyDispatcherFactory.CreateSetter ()
Boo.Lang.Runtime.RuntimeServices.DoCreatePropSetDispatcher (System.Object target, System.Type type, System.String name, System.Object value)
Boo.Lang.Runtime.RuntimeServices.CreatePropSetDispatcher (System.Object target, System.String name, System.Object value)
Boo.Lang.Runtime.RuntimeServices+<SetProperty>cAnonStorey16.<>mC ()
Boo.Lang.Runtime.DynamicDispatching.DispatcherCache.Get (Boo.Lang.Runtime.DynamicDispatching.DispatcherKey key, Boo.Lang.Runtime.DynamicDispatching.DispatcherFactory factory)
Boo.Lang.Runtime.RuntimeServices.Dispatch (System.Object target, System.String cacheKeyName, System.Type[] cacheKeyTypes, System.Object[] args, Boo.Lang.Runtime.DynamicDispatching.DispatcherFactory factory)
Boo.Lang.Runtime.RuntimeServices.Dispatch (System.Object target, System.String cacheKeyName, System.Object[] args, Boo.Lang.Runtime.DynamicDispatching.DispatcherFactory factory)
Boo.Lang.Runtime.RuntimeServices.SetProperty (System.Object target, System.String name, System.Object value)
DoDamageOnContact.OnCollisionEnter (UnityEngine.Collision hit) (at Assets/Scripts/Enemy&Asteroids/DoDamageOnContact.js:20)

Is this a bug or am I missing something?

Try this (not tested):

if(this.collider){
this.collider.enabled = false;
}
else
Debug.Log(“there is no collider attached along with this script”);