[BUG]: Incorrect return type hint for Phalcon\Db\Column::getAfterPosition()

[sergeyklay]

Current return type hint of the Phalcon\Db\Column::getAfterPosition implies that method must return an string value:

cphalcon/phalcon/Db/Column.zep

Lines 443 to 449 in 0532760

	/**
	* Check whether field absolute to position in table
	*/
	public function getAfterPosition() -> string
	{
	return this->after;
	}

But this method MAY return NULL:

cphalcon/phalcon/Db/Column.zep

Lines 208 to 214 in 0532760

	/**
	* Column Position
	*
	* @var string
	*/
	protected after;

and this leads to a fatal error:

PHP Fatal error:
Return value of Phalcon\Db\Column::getAfterPosition()
must be of the type string, null returned in Unknown on line 0

[sergeyklay]

Fixed in 4.0.x branch