Posted by abelsromero on Dec 04, 2018; 7:15am
URL: https://discuss.asciidoctor.org/Adding-Words-to-Title-Causes-Errors-tp6627p6628.html

Not sure about the line 6 error, but while the original example does no produce errors, it does not produce a correct output neither.
In v 1.5.6.1 and 1.5.8 the preface section is processed as part of the author and revision data.
Adding more text makes the confuses de parser in a bad manner.

This is an issue to me, but it points to an error in the source format. I am no expect, but I don't think that preface format is 100% correct, have you checked with https://asciidoctor.org/docs/user-manual/#user-preface?

About the issue in the book it would seem the doktype is not being correctly passed as a parameter to the asciidoctor command, and it is running in article mode.