Crash saving an event in the FE without an event type

[oliverklee]

(1/2) #1297759968 TYPO3\CMS\Extbase\Property\Exception

Exception while property mapping at property path "eventType": The identity property "OliverKlee\Seminars\Domain\Model\NullEventType:" is no UID.

at TYPO3\CMS\Extbase\Property\PropertyMapper->convert(array('__identity' => '9', 'internalTitle' => 'Created in the FE, too', 'description' => '', 'eventType' => 'OliverKlee\Seminars\Domain\Model\NullEventType:', 'start' => array('date' => '', 'dateFormat' => 'Y-m-d\TH:i'), 'end' => array('date' => '', 'dateFormat' => 'Y-m-d\TH:i'), 'earlyBirdDeadline' => array('date' => '', 'dateFormat' => 'Y-m-d\TH:i'), 'registrationDeadline' => array('date' => '', 'dateFormat' => 'Y-m-d\TH:i'), 'registrationRequired' => '', 'waitingList' => '', 'minimumNumberOfRegistrations' => '0', 'maximumNumberOfRegistrations' => '0', 'standardPrice' => '0', 'earlyBirdPrice' => '0', 'venues' => '', 'speakers' => '', 'organizers' => array('3')), 'OliverKlee\Seminars\Domain\Model\Event\SingleEvent', object(TYPO3\CMS\Extbase\Mvc\Controller\MvcPropertyMappingConfiguration))

[oliverklee]

This happens both when editing an event as well as when creating a new one.