Warning on installing Varbase 8.x-406

On installing Varbase 8.x-4.06, with all additional modules, and with development set to report all messages, with traceback, I get this message on the first display of the front page;

Warning: Invalid argument supplied for foreach() in Drupal\Component\Plugin\Discovery\DerivativeDiscoveryDecorator->getDerivatives() (line 102 of core/lib/Drupal/Component/Plugin/Discovery/DerivativeDiscoveryDecorator.php).
Drupal\Component\Plugin\Discovery\DerivativeDiscoveryDecorator->getDerivatives(Array) (Line: 87)
Drupal\Component\Plugin\Discovery\DerivativeDiscoveryDecorator->getDefinitions() (Line: 283)
Drupal\Core\Plugin\DefaultPluginManager->findDefinitions() (Line: 174)
Drupal\Core\Plugin\DefaultPluginManager->getDefinitions() (Line: 181)
Drupal\Core\Menu\LocalTaskManager->getDefinitions() (Line: 206)
Drupal\Core\Menu\LocalTaskManager->getLocalTasksForRoute('page_manager.page_view_homepage_homepage-panels_variant-0') (Line: 290)
Drupal\Core\Menu\LocalTaskManager->getTasksBuild('page_manager.page_view_homepage_homepage-panels_variant-0', Object) (Line: 358)
Drupal\Core\Menu\LocalTaskManager->getLocalTasks('page_manager.page_view_homepage_homepage-panels_variant-0', 0) (Line: 94)
Drupal\Core\Menu\Plugin\Block\LocalTasksBlock->build() (Line: 203)
Drupal\block\BlockViewBuilder::preRender(Array)
call_user_func('Drupal\block\BlockViewBuilder::preRender', Array) (Line: 376)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 448)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 195)
Drupal\Core\Render\Renderer->render(Array) (Line: 490)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 324)
__TwigTemplate_13d3c2eae859a78aa88f3ea0db24a6e10781ceeeff8fbbd3596c40bc202e7eec->block_header(Array, Array) (Line: 186)
Twig_Template->displayBlock('header', Array, Array) (Line: 214)
__TwigTemplate_13d3c2eae859a78aa88f3ea0db24a6e10781ceeeff8fbbd3596c40bc202e7eec->block_main(Array, Array) (Line: 186)
Twig_Template->displayBlock('main', Array, Array) (Line: 101)
__TwigTemplate_13d3c2eae859a78aa88f3ea0db24a6e10781ceeeff8fbbd3596c40bc202e7eec->doDisplay(Array, Array) (Line: 379)
Twig_Template->displayWithErrorHandling(Array, Array) (Line: 347)
Twig_Template->display(Array) (Line: 358)
Twig_Template->render(Array) (Line: 64)
twig_render_template('profiles/varbase/themes/vartheme/templates/system/page.html.twig', Array) (Line: 384)
Drupal\Core\Theme\ThemeManager->render('page', Array) (Line: 435)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 195)
Drupal\Core\Render\Renderer->render(Array) (Line: 490)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 106)
__TwigTemplate_831ccbb662f0d174146cd4ab0efef6eb4adbcc42eb4ea12b9f1326298d05e847->doDisplay(Array, Array) (Line: 379)
Twig_Template->displayWithErrorHandling(Array, Array) (Line: 347)
Twig_Template->display(Array) (Line: 358)
Twig_Template->render(Array) (Line: 64)
twig_render_template('profiles/varbase/themes/vartheme/templates/system/html.html.twig', Array) (Line: 384)
Drupal\Core\Theme\ThemeManager->render('html', Array) (Line: 435)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 195)
Drupal\Core\Render\Renderer->render(Array) (Line: 147)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 574)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 148)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('kernel.view', Object) (Line: 149)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 64)
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: 99)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 78)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 50)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 656)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

For what it's worth, this is instaled with PostgreSQL, but the nature of the warning doens't seem to indicate that database is an issue here.