Trying to access array offset on value of type null

Call Stack

1. in 2e7360ed0872b8151aedae130a68cac4.php line 257
2. at Error::appError() in 2e7360ed0872b8151aedae130a68cac4.php line 257
3. at include('/www/wwwroot/web.yon...') in File.php line 53
4. at File->read() in Template.php line 188
5. at Template->fetch() in Think.php line 86
6. at Think->fetch() in View.php line 163
7. at View->fetch() in Index.php line 241
8. at Index->cases_detail()
9. at call_user_func_array() in Route.php line 76
10. at Route->execute()
11. at ReflectionMethod->invokeArgs() in App.php line 343
12. at App::invokeMethod() in App.php line 470
13. at App::exec() in App.php line 139
14. at App::run() in start.php line 19
15. at require('/www/wwwroot/web.yon...') in index.php line 23