致命错误: Call to a member function combine() on null

Call Stack

1. in Question.php line 91
2. at Question->show()
3. at call_user_func_array([object(Question), 'show'], []) in Route.php line 78
4. at Route->execute('ask', 'question', 'show')
5. at ReflectionMethod->invokeArgs(object(Route), ['ask', 'question', 'show']) in App.php line 343
6. at App::invokeMethod(['\think\addons\Route', 'execute'], ['id' => '1', 'addon' => 'ask', 'controller' => 'question', ...]) in App.php line 470
7. at App::exec(['type' => 'method', 'method' => ['\think\addons\Route', 'execute'], 'var' => ['addon' => 'ask', 'controller' => 'question', 'action' => 'show']], ['app_host' => '', 'app_debug' => true, 'app_trace' => false, ...]) in App.php line 139
8. at App::run() in start.php line 19
9. at require('/www/wwwroot/gdtmast...') in index.php line 24