fix(logging): Restore the option to log with debug level

Signed-off-by: Joas Schilling <coding@schilljs.com>

lib/private/legacy/OC_User.php

@@ -39,9 +39,9 @@
 use OC\User\LoginException;
 use OCP\EventDispatcher\IEventDispatcher;
 use OCP\IGroupManager;
+use OCP\ISession;
 use OCP\IUser;
 use OCP\IUserManager;
-use OCP\IUserSession;
 use OCP\Server;
 use OCP\User\Events\BeforeUserLoggedInEvent;
 use OCP\User\Events\UserLoggedInEvent;
@@ -339,7 +339,7 @@ class OC_User {
 	 * @return string|false uid or false
 	 */
 	public static function getUser() {
-		$uid = Server::get(IUserSession::class)->getUser()?->getUID();
+		$uid = Server::get(ISession::class)?->get('user_id');
 		if (!is_null($uid) && self::$incognitoMode === false) {
 			return $uid;
 		} else {