Message on reload to hopefully stop the user.

assets/game1.js

@@ -60,6 +60,15 @@ document.addEventListener('DOMContentLoaded', async () => {
 
   // Look for config injected by Twig in the page
   const cfgEl = document.getElementById('mercure-config');
+
+  // Prevent/warn on page reload
+  window.addEventListener('beforeunload', (event) => {
+    // Standard way to trigger the browser's confirmation dialog
+    event.preventDefault();
+    // Included for compatibility with older browsers
+    event.returnValue = '';
+  });
+
   if (!cfgEl) {
     console.warn('[Mercure][game1] #mercure-config element not found on page');
     return;