Prep Plugin for release on WordPress.org

Escape everything that should be escaped.
Add nonce checks where needed.
Sanitize all inputs.
Apply Code style changes across the codebase.
Correct many deprecation notices.
Optimize load order of many filters.

inc/functions/markup-helpers.php

@@ -21,7 +21,7 @@ function wu_convert_to_state($state_array = []) {
 
 	$object = (object) $state_array; // Force object to prevent issues with Vue.
 
-	return json_encode($object);
+	return wp_json_encode($object);
 }
 
 /**