Attempt to assign property "timestamps" on null

Error: Attempt to assign property "timestamps" on null in file /opt/bitnami/projects/petra-backend/app/Http/Controllers/PostController.php on line 424 #0 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Controller.php(54): App\Http\Controllers\PostController->getUnauthSinglePost() #1 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/ControllerDispatcher.php(43): Illuminate\Routing\Controller->callAction() #2 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Route.php(260): Illuminate\Routing\ControllerDispatcher->dispatch() #3 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Route.php(205): Illuminate\Routing\Route->runController() #4 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Router.php(798): Illuminate\Routing\Route->run() #5 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(141): Illuminate\Routing\Router->Illuminate\Routing\{closure}() #6 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Middleware/SubstituteBindings.php(50): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #7 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(180): Illuminate\Routing\Middleware\SubstituteBindings->handle() #8 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Middleware/ThrottleRequests.php(126): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #9 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Middleware/ThrottleRequests.php(102): Illuminate\Routing\Middleware\ThrottleRequests->handleRequest() #10 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Middleware/ThrottleRequests.php(54): Illuminate\Routing\Middleware\ThrottleRequests->handleRequestUsingNamedLimiter() #11 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(180): Illuminate\Routing\Middleware\ThrottleRequests->handle() #12 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(116): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #13 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Router.php(799): Illuminate\Pipeline\Pipeline->then() #14 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Router.php(776): Illuminate\Routing\Router->runRouteWithinStack() #15 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Router.php(740): Illuminate\Routing\Router->runRoute() #16 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Routing/Router.php(729): Illuminate\Routing\Router->dispatchToRoute() #17 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(190): Illuminate\Routing\Router->dispatch() #18 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(141): Illuminate\Foundation\Http\Kernel->Illuminate\Foundation\Http\{closure}() #19 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/TransformsRequest.php(21): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #20 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/ConvertEmptyStringsToNull.php(31): Illuminate\Foundation\Http\Middleware\TransformsRequest->handle() #21 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(180): Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull->handle() #22 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/TransformsRequest.php(21): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #23 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/TrimStrings.php(40): Illuminate\Foundation\Http\Middleware\TransformsRequest->handle() #24 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(180): Illuminate\Foundation\Http\Middleware\TrimStrings->handle() #25 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/ValidatePostSize.php(27): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #26 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(180): Illuminate\Foundation\Http\Middleware\ValidatePostSize->handle() #27 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/PreventRequestsDuringMaintenance.php(86): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #28 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(180): Illuminate\Foundation\Http\Middleware\PreventRequestsDuringMaintenance->handle() #29 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Http/Middleware/HandleCors.php(62): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #30 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(180): Illuminate\Http\Middleware\HandleCors->handle() #31 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Http/Middleware/TrustProxies.php(39): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #32 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(180): Illuminate\Http\Middleware\TrustProxies->handle() #33 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Http/Middleware/TrustHosts.php(48): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #34 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(180): Illuminate\Http\Middleware\TrustHosts->handle() #35 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Pipeline/Pipeline.php(116): Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}() #36 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(165): Illuminate\Pipeline\Pipeline->then() #37 /opt/bitnami/projects/petra-backend/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(134): Illuminate\Foundation\Http\Kernel->sendRequestThroughRouter() #38 /opt/bitnami/projects/petra-backend/public/index.php(52): Illuminate\Foundation\Http\Kernel->handle() #39 {main}