wip-feat: mercure alerts

assets/app.js

@@ -8,3 +8,13 @@ import './bootstrap.js';
 import './styles/app.css';
 
 console.log('This log comes from assets/app.js - welcome to AssetMapper! 🎉');
+
+let alert = document.querySelector('.alert');
+var observer = new MutationObserver(function(mutations) {
+    if (document.contains(alert)) {
+        observer.disconnect();
+    }
+});
+
+observer.observe(document, {attributes: false, childList: true, characterData: false, subtree:true});
+