(...) can only be called on an active agent that has been placed on a NavMesh

If methods in Mover.cs throwing errors,

In ActionSchedular.cs

// Probably you typed like this:
        public void CancelCurrentAction()
        {
            currentAction = null;
        }
       /// ↑ ↑ This is wrong. Try to this one ↓
        public void CancelCurrentAction()
        {
            StartAction(null);
        }

I stuck with this and found the solution. Just wanted to share.