Trying to access array offset on value of type null

Call Stack

1. in WebCommon.php line 39
2. at Error->appError() in WebCommon.php line 39
3. at WebCommon->getCate() in Index.php line 47
4. at Index->cate()
5. at ReflectionMethod->invokeArgs() in Container.php line 344
6. at Container->invokeReflectMethod() in Controller.php line 110
7. at Controller->think\route\dispatch\{closure}() in Pipeline.php line 59
8. at Pipeline->think\{closure}() in Pipeline.php line 66
9. at Pipeline->then() in Controller.php line 113
10. at Controller->exec() in Dispatch.php line 80
11. at Dispatch->run() in Route.php line 793
12. at Route->think\{closure}() in Pipeline.php line 59
13. at Pipeline->think\{closure}() in Pipeline.php line 66
14. at Pipeline->then() in Route.php line 794
15. at Route->dispatch() in Http.php line 216
16. at Http->dispatchToRoute() in Http.php line 206
17. at Http->think\{closure}() in Pipeline.php line 59
18. at Pipeline->think\{closure}() in MultiApp.php line 51
19. at MultiApp->think\app\{closure}() in Pipeline.php line 59
20. at Pipeline->think\{closure}() in Pipeline.php line 66
21. at Pipeline->then() in MultiApp.php line 52
22. at MultiApp->handle()
23. at call_user_func() in Middleware.php line 142
24. at Middleware->think\{closure}() in Pipeline.php line 85
25. at Pipeline->think\{closure}() in SessionInit.php line 67
26. at SessionInit->handle()
27. at call_user_func() in Middleware.php line 142
28. at Middleware->think\{closure}() in Pipeline.php line 85
29. at Pipeline->think\{closure}() in TraceDebug.php line 71
30. at TraceDebug->handle()
31. at call_user_func() in Middleware.php line 142
32. at Middleware->think\{closure}() in Pipeline.php line 85
33. at Pipeline->think\{closure}() in Pipeline.php line 66
34. at Pipeline->then() in Http.php line 207
35. at Http->runWithRequest() in Http.php line 170
36. at Http->run() in index.php line 9