Fix coding configuration validity checks.

        self.k = k

        self.r = n - k

        if self.r != 0:

            if n_cycle is None:

                raise ValueError("n_cycle cannot be None if n == k.")

            elif sum(n_cycle) != (n-k):

        if self.r != 0 and n_cycle is None:

            raise ValueError("n_cycle cannot be None if (n-k) != 0.")

        if sum(n_cycle) != (n-k):

            raise ValueError("The elements in n_cycle must sum up to n-k.")

        self.n_cycle = n_cycle if n_cycle is not None else [0]