Remove redundant try-catch

[thewilkybarkid]

NotAnArticle will never be thrown due to

article-store/src/routes/add-article.ts

Lines 18 to 22 in 5758e15

	const id = clownface({ dataset: request.dataset }).has(rdf.type, schema.Article).term;
	if (!id) {
	throw new createHttpError.BadRequest(`No ${termToString(schema.Article)} found`);
	}

Found by #167.