In Zend\Db\TableGateway\AbstractTableGateway.php, we are not calling the parent constructor with the necessary parameters, so the adapter is never passed to the parent class. The constructor will fail if $this->databaseSchema has not been set in the $this->setup() method because $this->initialize() will get called, which in turn calls $this->adapter->getDefaultSchema(), which will fail because $this->adapter was never set. (because we are not calling the parent constructor properly).