This issue relates to issue 62411.
If an NPC such as an npc_human_grunt doesn’t have a weapon, and is aggressive towards the player, a crash can occur. The trigger is unknown, however I believe it has to do with attempting to throw a grenade and not null-checking the current weapon.
For reproducibility, see the issue linked at the top.
You can find the crash dump here.
EDIT: You can find the crash dump for public-beta branch here.