Closing nodes placed incorrectly when attached directly to root node

[McTano]

The node placement isn't working in a particular edge case.

If the initial set of formulas contains a contradiction, it's valid to close the tree right away, without appending any additional nodes. Likewise, you can close it with "O" if all formulas are already literals.
Currently if you do this, the closing node gets positioned behind the root node, instead of underneath it.