minor fix

ot_core/Classes/Domain/Repository/DonorRepository.php

@@ -65,7 +65,7 @@ class DonorRepository extends BaseApiRepository
         $donor->setWebsite($record['website']);
         $donor->setWording($record['wording']);
         $donor->setDisplayedOn($record['displayedOn']);
-        $donor->setLogo($record['logo']);
+        $donor->setLogo($record['logo'] ?? null);
 
         return $donor;
     }