Call to undefined method ReflectionUnionType::getName()

[TDBF]

Error: Call to undefined method ReflectionUnionType::getName() (0)
#0 C:\wamp64\www\invisiondev4.7dev\applications\core\modules\admin\applications\developer.php(3578): IPS\Plugin\_Hook->editForm(Object(IPS\Http\Url\Internal))
#1 C:\wamp64\www\invisiondev4.7dev\system\Dispatcher\Controller.php(107): IPS\core\modules\admin\applications\_developer->editHook()
#2 C:\wamp64\www\invisiondev4.7dev\applications\core\modules\admin\applications\developer.php(69): IPS\Dispatcher\_Controller->execute('do')
#3 C:\wamp64\www\invisiondev4.7dev\system\Dispatcher\Dispatcher.php(153): IPS\core\modules\admin\applications\_developer->execute()
#4 C:\wamp64\www\invisiondev4.7dev\admin\index.php(13): IPS\_Dispatcher->run()
#5 {main}

Added a hook to extend class \IPS\Content\Controller, I get this error when trying to edit the hook from the Developer Centre.

Using PHP 8.0.23

Edited February 25 by TDBF