Hi there!
That is strange, This method is used by old versions of Eli Book and my other plugins. The most updated versions of EliMZ_Book.js and EliMZ_MessageCommonEvent.js are, respectivelly: 6.1.2 and 1.3.0.
Make sure you have them both updated and EliMZ_Book is above any other EliMZ plugin.
If you are using the latest version of EliMZ_Book, you should see a customized error screen. Send me a screenshot of it when it happens. If not, press F12, a browser window will open. Go to the CONSOLE tab, and send me a screenshot of what is in there.