Call to a member function getSection() on null

I am also having this issue on a D9->D10 upgraded site that heavily uses Layout Builder. I can't recreate it on a site that started as Drupal 10. Can you detail more on where your proposed changes would go?

Are you patching core/layout builder? Your error message:

Error: Call to a member function getSection() on null in Drupal\layout_builder\Form\ConfigureBlockFormBase->getCurrentSection() (line 341 of /Applications/MAMP/htdocs/xxxxxx/docroot/core/modules/layout_builder/src/Form/ConfigureBlockFormBase.php).

There is no line 341 of ConfigureBlockFormBase in Drupal 10.2.x.

Patch #6 worked for me.
Thanks @kmani

The patch did not solve the issue for me. After I applied patch #6, I get a new error:

Error: Call to a member function getSection() on null in Drupal\layout_builder\Form\ConfigureBlockFormBase->getCurrentSection() (line 343 of /var/www/web/core/modules/layout_builder/src/Form/ConfigureBlockFormBase.php).

Backtrace:

#0 /var/www/web/core/modules/layout_builder/src/Form/ConfigureBlockFormBase.php(353): Drupal\layout_builder\Form\ConfigureBlockFormBase->getCurrentSection()
#1 /var/www/web/modules/contrib/layout_builder_styles/layout_builder_styles.module(50): Drupal\layout_builder\Form\ConfigureBlockFormBase->getCurrentComponent()
#2 /var/www/web/core/lib/Drupal/Core/Extension/ModuleHandler.php(552): layout_builder_styles_form_alter(Array, Object(Drupal\Core\Form\FormState), 'layout_builder_...')
#3 /var/www/web/core/lib/Drupal/Core/Form/FormBuilder.php(834): Drupal\Core\Extension\ModuleHandler->alter('form', Array, Object(Drupal\Core\Form\FormState), 'layout_builder_...')
#4 /var/www/web/core/lib/Drupal/Core/Form/FormBuilder.php(285): Drupal\Core\Form\FormBuilder->prepareForm('layout_builder_...', Array, Object(Drupal\Core\Form\FormState))
#5 /var/www/web/core/lib/Drupal/Core/Controller/FormController.php(73): Drupal\Core\Form\FormBuilder->buildForm(Object(Drupal\layout_builder\Form\AddBlockForm), Object(Drupal\Core\Form\FormState))
#6 [internal function]: Drupal\Core\Controller\FormController->getContentResult(Object(Symfony\Component\HttpFoundation\Request), Object(Drupal\Core\Routing\RouteMatch))
#7 /var/www/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array(Array, Array)
#8 /var/www/web/core/lib/Drupal/Core/Render/Renderer.php(638): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#9 /var/www/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(121): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure))
#10 /var/www/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array)
#11 /var/www/vendor/symfony/http-kernel/HttpKernel.php(181): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#12 /var/www/vendor/symfony/http-kernel/HttpKernel.php(76): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
#13 /var/www/web/core/lib/Drupal/Core/StackMiddleware/Session.php(53): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#14 /var/www/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(48): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#15 /var/www/web/core/lib/Drupal/Core/StackMiddleware/ContentLength.php(28): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#16 /var/www/web/core/modules/big_pipe/src/StackMiddleware/ContentLength.php(32): Drupal\Core\StackMiddleware\ContentLength->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#17 /var/www/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(106): Drupal\big_pipe\StackMiddleware\ContentLength->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#18 /var/www/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(85): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#19 /var/www/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(48): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#20 /var/www/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(51): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#21 /var/www/web/core/lib/Drupal/Core/StackMiddleware/AjaxPageState.php(36): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#22 /var/www/web/core/lib/Drupal/Core/StackMiddleware/StackedHttpKernel.php(51): Drupal\Core\StackMiddleware\AjaxPageState->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#23 /var/www/web/core/lib/Drupal/Core/DrupalKernel.php(741): Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#24 /var/www/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#25 {main}

I realized I was facing this issue because of the Reusable Block patch I applied related to https://www.drupal.org/project/drupal/issues/2999491.

Here's a patch to fix this issue when using Layout Builder Styles along with the Reusable Block patch.

Patch #9 solved my problem! Thanks, @carolpettirossi.