So this took me some time to find but it appears that if you add some NPCs to your party and do not add them to the DB_IsPlayer() database, any attempt to read your journal will crash the game.Steps to Reproduce
1. Create a quest with shared journal entries. It doesn't seem to matter whether the broadcast level is character, party, or user.
2. Use the DB_QuestDef_State() API and then advance the state of the quest by setting the associated QuestUpdate_Quest_State
3. Recruit an NPC into your party. Easiest thing is to use CharacterRecruitCharacter(), but I also tried permutations with CharacterMakePlayer()/CharacterAssignToUser()/CharacterAddToParty.
4. Open Journal
This can be resolved by simply adding DB_IsPlayer() for the NPC when it gets recruited. This seems like a bug as it should not be strictly necessary to rely on DB_IsPlayer(), but that seems to be an unwritten rule in a lot of the Osiris APIs.
We should at least get this documented somewhere in relevant portions of the wiki if it can't be fixed easily.