If you define rules on default Atk4\Data\Model class, then it do not …

…have $table set and will fail (#117)

src/Form/Control/GenericDropdown.php

@@ -33,7 +33,7 @@ public function getModel()
             return null;
         }
 
-        $model = new $class($this->form->entity->getModel()->getPersistence());
+        $model = new $class($this->form->entity->getModel()->getPersistence(), ['table' => '']);
         if (!$model instanceof Model) {
             throw new Exception('Class must be instance of ' . Model::class);
         }