If I have text analysis enabled for a comment form and post a comment, I get WSOD although the comment does actually get posted.
The log says this:
Drupal\Core\Database\IntegrityConstraintViolationException: SQLSTATE: Integrity constraint violation: 1048 Column 'reason' cannot be null:
I will try to investigate further in the next few days.
This is after the change I describe here https://www.drupal.org/node/2560147 to get the form to display.