issue in error handling Config load

src/opnsense/mvc/app/library/OPNsense/Core/Config.php

@@ -236,12 +236,17 @@ class Config extends Singleton
 
         set_error_handler(
             function() {
-                throw new ConfigException("invalid config xml") ;
+                // reset simplexml pointer on parse error.
+                $this->simplexml = null ;
             }
         );
 
         $this->simplexml = simplexml_load_string($xml);
 
+        if ($this->simplexml == null) {
+            throw new ConfigException("invalid config xml") ;
+        }
+
         restore_error_handler();
         $this->statusIsValid = true;
     }