diff --git a/public/js/app.js b/public/js/app.js
index caedc7b..925edf9 100644
--- a/public/js/app.js
+++ b/public/js/app.js
@@ -17,6 +17,11 @@ const App = {
     try { const s = await API.get('/install/status'); if (!s.installed) { location.hash = '#/install'; return; } } catch { location.hash = '#/install'; return; }
     this._footerLoaded = false;
     window.addEventListener('hashchange', () => this.route());
+    window.onerror = (msg, url, line, col, err) => {
+      console.error('JS Error:', msg, url, line, col);
+      const el = document.getElementById('sidebar-nav');
+      if (el) el.insertAdjacentHTML('beforeend', '<div style="color:red;font-size:10px;padding:8px">Error: ' + String(msg).substring(0,80) + '</div>');
+    };
     document.getElementById('modal-close').onclick = () => this.closeModal();
     document.addEventListener('click', (e) => {
       const action = e.target.closest('[data-action]');