I have webform 8.x-5.0-beta9 version and when i try to uninstall the module

using drush its asking me to uninstall webform_demo_application_evaluation

first  . When i tried drush pm-uninstall webform_demo_application_evaluation

Its throwing me error like as follows :

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] 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 to resolve this issue  ? Do i need to install the dev version ?

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?