fix: some page has no href for "issue".

[Wenzhi-Ding]

Test case added as well: https://www.foreignaffairs.com/united-states/real-china-trump-card-brooks-vagle

[AbeJellinek]

• We generally avoid const for things that aren't actually static constants (house style, I guess)
• It should be clearer that everything following the first line is a no-op if it doesn't match
• We already checked for issueNode's existence, and it definitely does have a parent (it isn't the Document node)

Suggested change

	const href = issueNode?.parentNode?.href || "";
	const issueMatch = href.match(/\/issues\/\d+\/(\d+)\/(\d+)$/);
	item.volume = issueMatch ? issueMatch[1] : "";
	item.issue = issueMatch ? issueMatch[2] : "";
	let href = issueNode.parentNode.href;
	if (href) {
	let issueMatch = href.match(/\/issues\/\d+\/(\d+)\/(\d+)$/);
	if (issueMatch) {
	item.volume = issueMatch[1];
	item.issue = issueMatch[2];
	}
	}