NullPointerException in the "OpenMarkov: Message window" when a middle state of a node is deleted

[Jorge Pérez]

When we delete one state of a node (unless it is the first or the last state) an exception appears in the OpenMarkov message window.

1 - Open node properties of a node with three or more states. 2 - Delete a mid state of the node 3 - See the log in the OpenMarkov message window

Despite this exception the program seems to run correctly

[Jorge Pérez]

Fixe issue #223. We check the boundaries only when variable type was Discretized or Numeric.