Thanks for the report. Sounds like an easy fix in the quest file or a perhaps not so easy compat bug fix. I'm not entirely sure what version of ZQuest DemoEX was last saved in, however. It might be from an old beta version and it should simply be updated to a 2.5 quest file in that case.
The one packaged with 2.10 is "version 2.10.1" and was made with 2.10. Gleeok's probably figured that out by now, but whatever. It's weird the error happens the same way in two different versions.