Notice: Undefined index: elements in template_preprocess_block()

PHP warnings showing across pages when a goback block was assigned into the region. Upon checking further, it seems that the missing elements array in the theme function causing the error. I've created a quick patch for a temporary fix. Looking forward for the permanent fix.

Here's the full error:

Notice: Undefined index: elements in template_preprocess_block() (line 221 of /public_html/core/modules/block/block.module)
#0 /public_html/core/includes/bootstrap.inc(600): _drupal_error_handler_real(8, 'Undefined index...', '/Users/madelync...', 221, Array)
#1 /public_html/core/modules/block/block.module(221): _drupal_error_handler(8, 'Undefined index...', '/Users/madelync...', 221, Array)
#2 /public_html/core/lib/Drupal/Core/Theme/ThemeManager.php(287): template_preprocess_block(Array, 'block__goback', Array)
#3 /public_html/core/lib/Drupal/Core/Render/Renderer.php(431): Drupal\Core\Theme\ThemeManager->render('block__goback', Array)
#4 /public_html/core/lib/Drupal/Core/Render/Renderer.php(200): Drupal\Core\Render\Renderer->doRender(Array, false)
#5 /public_html/core/lib/Drupal/Core/Template/TwigExtension.php(501): Drupal\Core\Render\Renderer->render(Array)
#6 /public_html/vendor/twig/twig/src/Environment.php(497) : eval()'d code(101): Drupal\Core\Template\TwigExtension->escapeFilter(Object(Drupal\Core\Template\TwigEnvironment), Array, 'html', NULL, true)
#7 /public_html/vendor/twig/twig/src/Template.php(214): __TwigTemplate_305c05248fcdbf6c5f35526fc71bf16a103177b0842459fa26779ccbeecb9975->block_content(Array, Array)
#8 /public_html/vendor/twig/twig/src/Environment.php(497) : eval()'d code(87): Twig\Template->displayBlock('content', Array, Array)
#9 /public_html/vendor/twig/twig/src/Template.php(453): __TwigTemplate_305c05248fcdbf6c5f35526fc71bf16a103177b0842459fa26779ccbeecb9975->doDisplay(Array, Array)
#10 /public_html/vendor/twig/twig/src/Template.php(420): Twig\Template->displayWithErrorHandling(Array, Array)
#11 /public_html/vendor/twig/twig/src/Template.php(432): Twig\Template->display(Array)
#12 /public_html/core/themes/engines/twig/twig.engine(64): Twig\Template->render(Array)
#13 /public_html/core/lib/Drupal/Core/Theme/ThemeManager.php(384): twig_render_template('themes/custom/b...', Array)
#14 /public_html/core/lib/Drupal/Core/Render/Renderer.php(431): Drupal\Core\Theme\ThemeManager->render('block', Array)
#15 /public_html/core/lib/Drupal/Core/Render/Renderer.php(200): Drupal\Core\Render\Renderer->doRender(Array, true)
#16 /public_html/core/lib/Drupal/Core/Render/Renderer.php(156): Drupal\Core\Render\Renderer->render(Array, true)
#17 /public_html/core/lib/Drupal/Core/Render/Renderer.php(573): Drupal\Core\Render\Renderer->Drupal\Core\Render\{closure}()
#18 /public_html/core/lib/Drupal/Core/Render/Renderer.php(157): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure))
#19 /public_html/core/lib/Drupal/Core/Render/Renderer.php(171): Drupal\Core\Render\Renderer->renderPlain(Array)
#20 /public_html/core/modules/big_pipe/src/Render/BigPipe.php(693): Drupal\Core\Render\Renderer->renderPlaceholder('callback=Drupal...', Array)
#21 /public_html/core/modules/big_pipe/src/Render/BigPipe.php(547): Drupal\big_pipe\Render\BigPipe->renderPlaceholder('callback=Drupal...', Array)
#22 /public_html/core/modules/big_pipe/src/Render/BigPipe.php(305): Drupal\big_pipe\Render\BigPipe->sendPlaceholders(Array, Array, Object(Drupal\Core\Asset\AttachedAssets))
#23 /public_html/core/modules/big_pipe/src/Render/BigPipeResponse.php(112): Drupal\big_pipe\Render\BigPipe->sendContent(Object(Drupal\big_pipe\Render\BigPipeResponse))
#24 /public_html/vendor/symfony/http-foundation/Response.php(374): Drupal\big_pipe\Render\BigPipeResponse->sendContent()
#25 /public_html/index.php(20): Symfony\Component\HttpFoundation\Response->send()
#26 {main}