fix build

docs/src/TiptapDemo.js

@@ -1,6 +1,7 @@
 import iframeResize from 'iframe-resizer/js/iframeResizer'
 
-class TiptapDemo extends HTMLElement {
+if (typeof window === 'object' && !window.process) {
+  class TiptapDemo extends HTMLElement {
     url = 'https://embed.tiptap.dev'
 
     connectedCallback() {
@@ -31,6 +32,7 @@ class TiptapDemo extends HTMLElement {
 
       observer.observe(wrapper)
     }
-}
+  }
 
-window.customElements.define('tiptap-demo', TiptapDemo)
+  window.customElements.define('tiptap-demo', TiptapDemo)
+}