fix: navigation on mobile

Author: nikhiltidke101

custom-implementation/src/main.tsx

@@ -17,16 +17,19 @@ const render = async () => {
    */
 
   const data = await getPageData()
-  const sidenav = document.querySelector('button.fern-search-bar')
-    ?.parentElement as HTMLElement
 
   const theme = document.getElementsByTagName('html')[0].getAttribute('class')
 
+  const sidenav = document.querySelector('button.fern-search-bar')
+    ?.parentElement as HTMLElement
+
   if (!document.getElementById('theme-switch')) {
     const wrapper = document.createElement('div')
     wrapper.setAttribute('id', 'theme-switch')
-    sidenav.appendChild(wrapper)
-    ReactDOM.render(React.createElement(ThemeSwitch), wrapper)
+    if (sidenav) {
+      sidenav.appendChild(wrapper)
+      ReactDOM.render(React.createElement(ThemeSwitch), wrapper)
+    }
   }
 
   ReactDOM.render(