refactor: rewrite ajaxify.parseData in vanilla

public/src/ajaxify.js

@@ -311,12 +311,18 @@ ajaxify.widgets = { render: render };
 		app.processPage();
 	};
 
-	ajaxify.parseData = function () {
-		const dataEl = $('#ajaxify-data');
-		if (dataEl.length) {
-			ajaxify.data = JSON.parse(dataEl.text());
+	ajaxify.parseData = () => {
+		const dataEl = document.getElementById('ajaxify-data');
+		if (dataEl) {
+			try {
+				ajaxify.data = JSON.parse(dataEl.textContent);
+			} catch (e) {
+				console.error(e);
+				ajaxify.data = {};
+			} finally {
 				dataEl.remove();
 			}
+		}
 	};
 
 	ajaxify.removeRelativePath = function (url) {