framework/RedKiteCms/Content/PageCollection/PageCollectionBase.php
protected function contributorDefined()
    {
        if (null === $this->username && !$this->configurationHandler->isTheme()) {
            $exception = array(
                "message" => 'exception_contributor_not_defined',
                "show_exception" => true,
            );
            throw new LogicException(json_encode($exception));
        }
    }
protected function contributorDefined()
    {
        if (null === $this->username && !$this->configurationHandler->isTheme()) {
            $exception = array(
                "message" => 'exception_contributor_not_defined',
                "show_exception" => true,
            );
            throw new LogicException(json_encode($exception));
        }
    }
Checks the page contributor has been set