Update tools/doc/html.js

Co-authored-by: Antoine du Hamel <duhamelantoine1995@gmail.com>

Author: Trott

tools/doc/html.js

@@ -73,6 +73,9 @@ function processContent(content) {
   if (content.includes('<h6>')) {
     throw new Error('Cannot increment a level 6 header');
   }
+  if (/<h[1-5][^>]/.test(content) {
+    throw new Error('Cannot parse header tag with attributes');
+  }
   content.replace(/(?<=<\/?h)[1-5](?=>)/g, (level) => level + 1);
   // Wrap h3 tags in section tags.
   let firstTime = true;