[BUGFIX] Prevent JS crash

Resources/Public/JavaScript/CategoryFilter.js

@@ -34,8 +34,10 @@ export default class CategoryFilter {
 	 */
 	constructor(_newsList) {
 		this._newsList = _newsList;
-		this._form = this._newsList.querySelector('form');
-		this._setupEventListeners();
+		if (this._newsList) {
+			this._form = this._newsList.querySelector('form');
+			this._setupEventListeners();
+		}
 	}
 
 	/**