particular_path and array_key_exists() expects parameter 2 to be array, null given

    Notice: Undefined index: particular_path in Drupal\go_back\Plugin\Block\GoBack->blockSubmit() (line 280 of modules\go_back\src\Plugin\Block\GoBack.php).

    Drupal\go_back\Plugin\Block\GoBack->blockSubmit(Array, Object) (Line: 229)
    Drupal\Core\Block\BlockBase->submitConfigurationForm(Array, Object) (Line: 344)
    Drupal\block\BlockForm->submitForm(Array, Object)
    call_user_func_array(Array, Array) (Line: 111)
    Drupal\Core\Form\FormSubmitter->executeSubmitHandlers(Array, Object) (Line: 51)
    Drupal\Core\Form\FormSubmitter->doSubmitForm(Array, Object) (Line: 590)
    Drupal\Core\Form\FormBuilder->processForm('block_form', Array, Object) (Line: 319)
    Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 93)
    Drupal\Core\Controller\FormController->getContentResult(Object, Object)
    call_user_func_array(Array, Array) (Line: 123)
    Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 582)
    Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
    Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
    Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 151)
    Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 68)
    Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57)
    Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
    Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
    Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
    Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
    Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 52)
    Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
    Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 693)
    Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

    Warning: array_key_exists() expects parameter 2 to be array, null given in Drupal\go_back\Plugin\Block\GoBack->blockSubmit() (line 280 of modules\go_back\src\Plugin\Block\GoBack.php).

    Drupal\go_back\Plugin\Block\GoBack->blockSubmit(Array, Object) (Line: 229)
    Drupal\Core\Block\BlockBase->submitConfigurationForm(Array, Object) (Line: 344)
    Drupal\block\BlockForm->submitForm(Array, Object)
    call_user_func_array(Array, Array) (Line: 111)
    Drupal\Core\Form\FormSubmitter->executeSubmitHandlers(Array, Object) (Line: 51)
    Drupal\Core\Form\FormSubmitter->doSubmitForm(Array, Object) (Line: 590)
    Drupal\Core\Form\FormBuilder->processForm('block_form', Array, Object) (Line: 319)
    Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 93)
    Drupal\Core\Controller\FormController->getContentResult(Object, Object)
    call_user_func_array(Array, Array) (Line: 123)
    Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 582)
    Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
    Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
    Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 151)
    Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 68)
    Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57)
    Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
    Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
    Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
    Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
    Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 52)
    Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
    Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 693)
    Drupal\Core\DrupalKernel->handle(Object) (Line: 19)