getCacheTagsToInvalidate() called on null when uninstalling Page Manager module

I'm having issues uninstalling the Page Manager module. When uninstalling, I get the following error. As a method is called on null, this indicates a bug. The error occurs both when uninstalling through the UI or through drush. After a cache rebuild (drush cr all) the problem seems to be gone, but I thought this might still be worth reporting.

# drush pm-uninstall page_manager
The following extensions will be uninstalled: page_manager
Do you really want to continue? (y/n): y
PHP Fatal error:  Call to a member function getCacheTagsToInvalidate() on null in /[path_to_drupal]/modules/page_manager/src/Entity/PageVariant.php on line 179

Fatal error: Call to a member function getCacheTagsToInvalidate() on null in /[path_to_drupal]/modules/page_manager/src/Entity/PageVariant.php on line 179
Drush command terminated abnormally due to an unrecoverable error.                                                                                                                                  [error]
Error: Call to a member function getCacheTagsToInvalidate() on null in /[path_to_drupal]/modules/page_manager/src/Entity/PageVariant.php, line 179