message: fix: crash on 2-level md heading at the beginning
diff: @@ -98,7 +98,10 @@ export class MarkdownRenderer {
  `<a class="share-link" href="#${id}"></a>`
  );
  } else if (tokens[idx].hLevel === 2) {
  - const { id } = this.saveHeading(content, this.currentTopHeading.items);
  + const { id } = this.saveHeading(
  + content,
  + this.currentTopHeading && this.currentTopHeading.items,
  + );
  return (
  `<a name="${id}"></a>` +
  `<h${tokens[idx].hLevel} ${SECTION_ATTR}="${id}" id="${id}">` +
  