Ambiguous error message for unauthorized prepublication access

[ewhanson]

If an authenticated user/API key is required for access and the request is not authorized, the message returned via OAI is the same as when no JATS is found (Cannot disseminate format (JATS XML not available)), see:

oaiJats/OAIMetadataFormat_JATS.php

Lines 99 to 105 in 2974473

	$subscriptionRequired = $issueAction->subscriptionRequired($issue, $journal);
	$isSubscribedDomain = $issueAction->subscribedDomain(Application::get()->getRequest(), $journal, $issue->getId(), $article->getId());
	$allowedPrePublicationAccess = $issueAction->allowedIssuePrePublicationAccess($journal, $request->getUser());
	if ($subscriptionRequired && (!$allowedPrePublicationAccess && !$isSubscribedDomain)) {
	$oaiDao->oai->error('cannotDisseminateFormat', 'Cannot disseminate format (JATS XML not available)');
	exit();
	}

This should return a distinct message, indicating the type of error (why it cannot disseminate format)—that the record requires the request to include an authenticated user or API key with the correct access permissions.

This causes difficulties for downstream consumers of the OAI JATS metadata because it is not clear why OJS is failing to return the expected JATS XML.