lib(get-hml): remove all other classes than the ones we want to keep

Co-authored-by: Oscar Dominguez <dominguez.celada@gmail.com>

lib/get-html.ts

@@ -31,9 +31,20 @@ export const getHtml = async (
   $('[data-testid="callout"]').remove();
   const data = $("#article-contents").parent().parent();
   data.find("*").each((i, el) => {
-    const classes = $(el).attr("class") ?? "";
-    if (!classes.includes("language-json") && !classes.includes("warning")) {
-      $(el).removeAttr("class");
+    const classes = $(el).attr("class");
+
+    if (classes) {
+      const filteredClasses = classes
+        .split(" ")
+        .filter((classSelector) =>
+          ["language-json", "warning"].includes(classSelector)
+        );
+
+      if (filteredClasses.length) {
+        $(el).attr("class", filteredClasses.join(" "));
+      } else {
+        $(el).removeAttr("class");
+      }
     }
   });
   const html = data.html() ?? "";