Problem/Motivation
When I use layout builder there are following issues :
Warning: Undefined variable $region in abc_preprocess_block() (line 738 of themes\contrib\abc\abc.theme).
abc_preprocess_block(Array, 'block', Array)
call_user_func_array('abc_preprocess_block', Array) (Line: 285)
Drupal\Core\Theme\ThemeManager->render('block', Array) (Line: 436)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array) (Line: 474)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 52)
__TwigTemplate_420f310811ec8cdd1556b2ef88415659->doDisplay(Array, Array) (Line: 394)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 367)
Twig\Template->display(Array) (Line: 379)
Twig\Template->render(Array, Array) (Line: 40)
Twig\TemplateWrapper->render(Array) (Line: 53)
twig_render_template('core/modules/layout_discovery/layouts/onecol/layout--onecol.html.twig', Array) (Line: 372)
Drupal\Core\Theme\ThemeManager->render('layout__onecol', Array) (Line: 436)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array) (Line: 474)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 147)
__TwigTemplate_214a6b2e57291e7ef35c6da4d16b398a->doDisplay(Array, Array) (Line: 394)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 367)
Twig\Template->display(Array) (Line: 379)
Twig\Template->render(Array, Array) (Line: 40)
Twig\TemplateWrapper->render(Array) (Line: 53)
twig_render_template('themes/contrib/abc/templates/content/node.html.twig', Array) (Line: 372)
Drupal\Core\Theme\ThemeManager->render('node', Array) (Line: 436)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array, ) (Line: 238)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 583)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 239)
Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array, Object, Object) (Line: 128)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object)
call_user_func(Array, Object, 'kernel.view', Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object, 'kernel.view') (Line: 171)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 2) (Line: 74)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 2, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 2, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 2, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 2, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 2, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 2, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 2, 1) (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 2) (Line: 89)
Drupal\view_mode_page\Controller\MainController->displayEntity('dashboard_list', 'node', '93')
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 583)
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: 166)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 74)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
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: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 1, 1) (Line: 704)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)
Warning: Undefined variable $region in abc_preprocess_block() (line 750 of themes\contrib\abc\abc.theme).
abc_preprocess_block(Array, 'block', Array)
call_user_func_array('abc_preprocess_block', Array) (Line: 285)
Drupal\Core\Theme\ThemeManager->render('block', Array) (Line: 436)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array) (Line: 474)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 52)
__TwigTemplate_420f310811ec8cdd1556b2ef88415659->doDisplay(Array, Array) (Line: 394)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 367)
Twig\Template->display(Array) (Line: 379)
Twig\Template->render(Array, Array) (Line: 40)
Twig\TemplateWrapper->render(Array) (Line: 53)
twig_render_template('core/modules/layout_discovery/layouts/onecol/layout--onecol.html.twig', Array) (Line: 372)
Drupal\Core\Theme\ThemeManager->render('layout__onecol', Array) (Line: 436)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 449)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array) (Line: 474)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 147)
__TwigTemplate_214a6b2e57291e7ef35c6da4d16b398a->doDisplay(Array, Array) (Line: 394)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 367)
Twig\Template->display(Array) (Line: 379)
Twig\Template->render(Array, Array) (Line: 40)
Twig\TemplateWrapper->render(Array) (Line: 53)
twig_render_template('themes/contrib/abc/templates/content/node.html.twig', Array) (Line: 372)
Drupal\Core\Theme\ThemeManager->render('node', Array) (Line: 436)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 204)
Drupal\Core\Render\Renderer->render(Array, ) (Line: 238)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 583)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 239)
Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array, Object, Object) (Line: 128)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object)
call_user_func(Array, Object, 'kernel.view', Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object, 'kernel.view') (Line: 171)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 2) (Line: 74)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 2, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 2, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 2, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 2, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 2, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 2, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 2, 1) (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 2) (Line: 89)
Drupal\view_mode_page\Controller\MainController->displayEntity('dashboard_list', 'node', '93')
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 583)
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: 166)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 74)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
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: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 1, 1) (Line: 704)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)