I have definitely done something horribly wrong, but I'm not sure what.  I made a change to a state (I really don't remember what) and now when I click on that state two things happen:
1) The Console gets a ton of these errors: 
NullReferenceException: Object reference not set to an instance of an object
HutongGames.PlayMakerEditor.ActionEditor.EditFsmVar (System.Object fieldValue, System.Object[] attributes)
2) The Playmaker window goes completely blank.  (see attachment)  Since there's no way to unselect that state, I now have this blank window when I click on the gameobject.
While this doesn't crash Unity or anything, it's still pretty bad.  How do I get out of those state?  Is there any way for me to recover what was inside that state?  It had a number of actions in it, all of which I don't remember exactly.  I would prefer not to have to rebuild it from memory.  
Most importantly, what can I do to prevent this from happening again?  I've had plenty of those errors before but it's never caused the blank window issue.
Thank you,
Jenna