When holding down shift and pressing an arrow key to move servers in my server list, if I move it when it is already at the bottom of the list, and press shift+down, it crashed Minecraft.
After restarting Minecraft, I was unable to do it again, for some reason. I wasn't paying attention the first time it happened, but my theory is that if the "scanning for games on your local network" message ever goes away (I don't know if it can. I've never noticed it going away), that it crashes the game because I can use my arrow keys to select the message when it is there.
I've attached the crash report. I hope you can recreate this and don't think I'm crazy.
Looks like you're using optifine. If you load up non-modded Minecraft and try again, does it still happen?