I can't uninstall the Webform module I have the Webform module version  8.x-5.0-beta9, and when I try to uninstall the module Drush asks me to uninstall the webform_demo_application_evaluation module, first. When I try
drush pm-uninstall webform_demo_application_evaluation, it throws an error.


  PHP Fatal error: Call to a member function getColumns() on boolean in
  /var/www-drupal/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php on
  line 227
  Drush command terminated abnormally due to an unrecoverable error.
  Error: Call to a member function getColumns() on boolean in /var/www-drupal/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php, line 227


How do I resolve this issue? Do I need to install the development snapshot?
You should be able to manually delete the demo forms, blocks, and nodes and then uninstall the demo module.

Please create a ticket in the Webform issue queue.