Attempt to read property "id" on null

ErrorException: Attempt to read property "id" on null in file /www/wwwroot/snp24-backend/app/Http/Controllers/Api/V1/ArticleController.php on line 122 #0 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Foundation/Bootstrap/HandleExceptions.php(255): Illuminate\Foundation\Bootstrap\HandleExceptions->handleError() #1 /www/wwwroot/snp24-backend/app/Http/Controllers/Api/V1/ArticleController.php(122): Illuminate\Foundation\Bootstrap\HandleExceptions->Illuminate\Foundation\Bootstrap\{closure}() #2 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Controller.php(54): App\Http\Controllers\Api\V1\ArticleController->getArticleByCategory() #3 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/ControllerDispatcher.php(43): Illuminate\Routing\Controller->callAction() #4 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Route.php(259): Illuminate\Routing\ControllerDispatcher->dispatch() #5 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Route.php(205): Illuminate\Routing\Route->runController() #6 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Router.php(806): Illuminate\Routing\Route->run() #7 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(144): Illuminate\Routing\Router->Illuminate\Routing\{closure}() #8 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Middleware/SubstituteBindings.php(50): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #9 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(183): Illuminate\Routing\Middleware\SubstituteBindings->handle() #10 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Middleware/ThrottleRequests.php(159): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #11 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Middleware/ThrottleRequests.php(125): Illuminate\Routing\Middleware\ThrottleRequests->handleRequest() #12 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Middleware/ThrottleRequests.php(87): Illuminate\Routing\Middleware\ThrottleRequests->handleRequestUsingNamedLimiter() #13 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(183): Illuminate\Routing\Middleware\ThrottleRequests->handle() #14 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(119): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #15 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Router.php(805): Illuminate\Pipeline\Pipeline->then() #16 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Router.php(784): Illuminate\Routing\Router->runRouteWithinStack() #17 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Router.php(748): Illuminate\Routing\Router->runRoute() #18 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Routing/Router.php(737): Illuminate\Routing\Router->dispatchToRoute() #19 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(200): Illuminate\Routing\Router->dispatch() #20 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(144): Illuminate\Foundation\Http\Kernel->Illuminate\Foundation\Http\{closure}() #21 /www/wwwroot/snp24-backend/vendor/livewire/livewire/src/Features/SupportDisablingBackButtonCache/DisableBackButtonCacheMiddleware.php(19): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #22 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(183): Livewire\Features\SupportDisablingBackButtonCache\DisableBackButtonCacheMiddleware->handle() #23 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/TransformsRequest.php(21): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #24 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/ConvertEmptyStringsToNull.php(31): Illuminate\Foundation\Http\Middleware\TransformsRequest->handle() #25 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(183): Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull->handle() #26 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/TransformsRequest.php(21): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #27 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/TrimStrings.php(40): Illuminate\Foundation\Http\Middleware\TransformsRequest->handle() #28 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(183): Illuminate\Foundation\Http\Middleware\TrimStrings->handle() #29 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/ValidatePostSize.php(27): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #30 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(183): Illuminate\Foundation\Http\Middleware\ValidatePostSize->handle() #31 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/PreventRequestsDuringMaintenance.php(99): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #32 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(183): Illuminate\Foundation\Http\Middleware\PreventRequestsDuringMaintenance->handle() #33 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Http/Middleware/HandleCors.php(62): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #34 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(183): Illuminate\Http\Middleware\HandleCors->handle() #35 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Http/Middleware/TrustProxies.php(39): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #36 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(183): Illuminate\Http\Middleware\TrustProxies->handle() #37 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(119): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #38 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(175): Illuminate\Pipeline\Pipeline->then() #39 /www/wwwroot/snp24-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(144): Illuminate\Foundation\Http\Kernel->sendRequestThroughRouter() #40 /www/wwwroot/snp24-backend/public/index.php(51): Illuminate\Foundation\Http\Kernel->handle() #41 {main}