@Galadur: I figured it out and have a fix. You hit a scenario I didn't test.
Good job! You earned 1 xp!
I posted an update to Forge, so you should be all set for your next game.
Thanks for reporting it!
Here's the now deceased bug:
If the "show planning section" option has never been toggled on, when dropping an edge (or anything) onto a character's advances list, you get an "attempt to index a nil value" error.