In its section Properties of binary trees Wikipedia states:
The maximum possible number of null links (i.e., absent children of the nodes) in a complete binary tree of n nodes is (n+1), where only 1 node exists in bottom-most level to the far left.
I wonder about the precise statement used here. In my opinion every binary tree with $n$ nodes has exactly $n+1$ nil links (or missing children). A proof by induction is easy. (In fact that is equivalent to the statement some lines above: "a perfect binary tree with $\ell$ leaves has $n=2\ell-1$ nodes".)
Question: what am I missing here? Has Wikipedia different assumptions on binary trees?
As an illustration, a non-complete binary tree with 12 nodes and 13 nil-pointers, marked as square nodes. It can also been seen as a perfect binary tree with 25 nodes, the squares indicating leafs.