[BUG]: Incorrect return type hint of Phalcon\Mvc\Model\Resultset::getFirst

[sergeyklay]

The current implementation of Phalcon\Mvc\Model\Resultset::getFirst implies that method must return a Phalcon\Mvc\ModelInterface instance or NULL:

cphalcon/phalcon/Mvc/Model/Resultset.zep

Lines 311 to 320 in 00fb495

	public function getFirst() -> <ModelInterface> | null
	{
	if this->count == 0 {
	return null;
	}
	this->seek(0);
	return this->{"current"}();
	}

But in some case, it MAY return a Phalcon\Mvc\Model\Row instance:

$robots = new Robots();
$manager = $model->getModelsManager();

/** @var \Phalcon\Mvc\Model\Query $query */
$query = $manager->createQuery('SELECT r.id FROM Robots AS r');

/** @var \Phalcon\Mvc\Model\Resultset\Simple $result */
$result = $query->execute();

/** @var \Phalcon\Mvc\Model\Row $result */
$result->getFirst();

This leads to a fatal error:

PHP Fatal error:
Return value of Phalcon\Mvc\Model\Resultset::getFirst()
must implement interface Phalcon\Mvc\ModelInterface or be null,
instance of Phalcon\Mvc\Model\Row returned in Unknown on line 0

[niden]

Implemented in v4.0.x

[konkov-alexey]

the same problem with getLast() method in 4.0.6