fix(comment/waline): cannot read property ‘insertBefore’ of null (#1103)

* fix: resolve issue with comments not displaying due to KaTeX and Waline render order

* Fix the problem that comment data couldn't be pulled successfully and raise Error "Cannot read property ‘insertBefore’ of null""

layouts/partials/article/components/math.html

@@ -1,7 +1,8 @@
 {{- partial "helper/external" (dict "Context" . "Namespace" "KaTeX") -}}
 <script>
     window.addEventListener("DOMContentLoaded", () => {
-        renderMathInElement(document.body, {
+	const mainArticleElement = document.querySelector(".main-article");
+        renderMathInElement(mainArticleElement, {
             delimiters: [
                 { left: "$$", right: "$$", display: true },
                 { left: "$", right: "$", display: false },
@@ -10,4 +11,4 @@
             ],
             ignoredClasses: ["gist"]
         });})
-</script>
+</script>