Almost each /mod/{modulename}/index.php file provide a page beaking html strict standard.

The offending line is: $table->data[] = 'hr';
It adds an html like <td colspan="xx"> that is not allowed if not included into a tr tag.
The bug is in /lib/outputcomponents.php

To reproduce the bug simply...
-> Go to a course divided into sections
-> add two instances of the module :modulename INTO TWO DIFFERENT sections.
-> visit the page mod/:modulename/index.php?id=:courseid
-> make an html validation

To fix the issue:
apply the patch I provided.

In the frame of this issue, please, find a word to explain me why https://github.com/moodlehq/moodle-mod_newmodule/blob/master/index.php still uses add_to_log