WSOD when EventInstance has invalid translation.

I have a site, where an eventinstance somehow ended up in a wrong translation state.
That means that now, I'm stuck - unable to edit, delete nor view the eventseries.

I cant even use "drush entity:delete" as it fails:

InvalidArgumentException: Invalid translation language (da) specified. in Drupal\Core\Entity\ContentEntityBase->getTranslation() (line 903 of core/lib/Drupal/Core/Entity/ContentEntityBase.php).

I've debugged my way to /src/Plugin/ComputedField/EventInstances.php where I can see that we use ->getTranslation without checking if it exists.

I'll add a merge request.