fix: explicit undefined check in header transclude

Jacky Zhao

2023-11-19 516d9a27e7e2c08efdf24857b03f1831dbaf7da7

 quartz/components/pages/TagContent.tsx

@@ -53,7 +53,7 @@
            return (
              <div>
                <h2>
                  <a class="internal tag-link" href={`./${tag}`}>
                  <a class="internal tag-link" href={`../tags/${tag}`}>
                    #{tag}
                  </a>
                </h2>