[0.90.6] Crash on clicking Tech button

[johnlukeg]

Opening up the research menu in any way is causing my game to crash. This started happening after I tried building some walls and was unable to get my characters to path to the gate in order to add building materials. I had rebuilt the nav mesh a few times then gave up and reloaded. Not sure if it's related, since I made this save before I messed with all that. If it's not related, I have no idea.