Summoning a familiar may cause to join NPC faction in vanilla NWN party + crash

[Eraamion]

I was at the end of the new scripted quest in the Foothills. I summoned the familiar and suddenly I was in a party of 30+ NPCs, seeing their portraits on the right (mostly named Mercenary). The game froze and crashed for me, though the server did not. This never happened to me before when summoning a familiar.