message: fix(md-enhance): fix issues when mermaid takes long time to render
diff: @@ -84,7 +84,7 @@ export default defineComponent({
  const svgCode = ref("");
  const mermaidElement = ref<HTMLElement>();
  const isDarkmode = ref(false);
  - let observer: MutationObserver;
  + let observer: MutationObserver | null = null;
  onMounted(() => {
  const html = document.querySelector("html") as HTMLElement;
  @@ -161,7 +161,7 @@ export default defineComponent({
  });
  onBeforeUnmount(() => {
  - observer.disconnect();
  + observer?.disconnect();
  });
  return (): VNode =>
  