! php8.0 can throw undefined error when using unset on an array key

in an array that does exist but the key may not.  Plus the intention
of that line was to ensure only on option was set
! Nulling out the cookie name will cause set cookie to fail and lock
you out of the fourm

sources/admin/ManageServer.controller.php

@@ -221,12 +221,15 @@ public function action_cookieSettings_display()
 			call_integration_hook('integrate_save_cookie_settings');
 
 			// Its either local or global cookies
-			if (!empty($this->_req->post->localCookies) && empty($this->_req->post->globalCookies))
+			if (!empty($this->_req->post->localCookies) && !empty($this->_req->post->globalCookies))
 				unset($this->_req->post->globalCookies);
 
 			if (!empty($this->_req->post->globalCookiesDomain) && strpos($boardurl, $this->_req->post->globalCookiesDomain) === false)
 				throw new Elk_Exception('invalid_cookie_domain', false);
 
+			if ($this->_req->getPost('cookiename', 'trim', '') === '')
+				$this->_req->post->cookiename = $cookiename;
+
 			$settingsForm->setConfigValues((array) $this->_req->post);
 			$settingsForm->save();