A Quest Book user reported issues with his game crashing (Drethic/QuestBook#8). While reviewing his log file (https://gist.github.com/Dream-Master/6076e110aad8a5527dd8e0ee1d078a9c) I saw several references to PacketQuesting.java which I don't currently leverage. Based on user response and what the logs (snippets: http://pastebin.com/9hjBWeLb) say the error seems to happen during HQM Imports.

They are using the following mods:
Better Questing 1.0.79
StandardExpansion-1.0.56
questbook-1.1.0
RFExpansion-1.0.5.jar
NPCIntegration-1.0.6.jar
bq_themed-1.0.0.jar

I can give your more info if you need some.

Drethic/QuestBook#8

As of the latest builds, this has been fixed.