Issue: Undefined variable: numbers

ErrorException: Undefined variable: numbers - vault/core/controller/ui/book/vw.php:665 
Generated By: Alfa, A moment ago

Stack Trace
#0 /vault/core/controller/ui/book/vw.php(665): XenForo_Application::handlePhpError(8, 'Undefined varia...', '/home/...', 665, Array)
#1 /vault/core/controller/ui/book/vw.php(422): vw_UI_Book_Controller->asort_chapters()
#2 /vault/core/controller/ui/book/vw.php(39): vw_UI_Book_Controller->order()
#3 /vault/core/controller/ui/stack/vw.php(276): vw_UI_Book_Controller->execute()
#4 /library/vw/XenForo/ControllerPublic/Wiki.php(70): vw_UI_Stack_Controller->execute()
#5 /library/XenForo/FrontController.php(351): vw_XenForo_ControllerPublic_Wiki->actionIndex()
#6 /library/XenForo/FrontController.php(134): XenForo_FrontController->dispatch(Object(XenForo_RouteMatch))
#7 /index.php(13): XenForo_FrontController->run()
#8 {main}
Request State
array(3) {
  ["url"] => string(69) "https://my-forum.com/wiki/Book:xxx?do=order"
  ["_GET"] => array(1) {
    ["do"] => string(5) "order"
  }
  ["_POST"] => array(4) {
    ["number"] => array(4) {
      [52] => string(1) "1"
      [53] => string(1) "2"
      [54] => string(1) "3"
      [55] => string(1) "4"
    }
    ["_xfToken"] => string(8) "********"
    ["do"] => string(5) "order"
    ["type"] => array(1) {
      ["asort"] => string(11) "Alphabetize"
    }
  }
}