Hi there! ^^
Let's figure this out:
1 - When the error happens, press F8 or F12. A browser window will open, go to the CONSOLE tab, and send me a screenshot of the error there.
2 - Make sure you are using the latest versions of the RPG Maker Core plugins and my plugins too.
3 - See if your Eli Book is for MZ. The filename starts with EliMZ...
If none of that works, you can send me a sample project replicating the issue on my discord: hakuenstudio