Error message

Warning: Undefined array key 1 in Drupal\Core\Asset\LibraryDependencyResolver->doGetDependencies() (line 67 of core/lib/Drupal/Core/Asset/LibraryDependencyResolver.php).

Drupal\Core\Asset\LibraryDependencyResolver->doGetDependencies() (Line: 70)
Drupal\Core\Asset\LibraryDependencyResolver->doGetDependencies() (Line: 70)
Drupal\Core\Asset\LibraryDependencyResolver->doGetDependencies() (Line: 41)
Drupal\Core\Asset\LibraryDependencyResolver->getLibrariesWithDependencies() (Line: 116)
Drupal\Core\Asset\AssetResolver->getLibrariesToLoad() (Line: 175)
Drupal\Core\Asset\AssetResolver->getCssAssets() (Line: 323)
Drupal\Core\Render\HtmlResponseAttachmentsProcessor->processAssetLibraries() (Line: 167)
Drupal\Core\Render\HtmlResponseAttachmentsProcessor->processAttachments() (Line: 45)
Drupal\Core\EventSubscriber\HtmlResponseSubscriber->onRespond()
call_user_func() (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch() (Line: 214)
Symfony\Component\HttpKernel\HttpKernel->filterResponse() (Line: 202)
Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 76)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 53)
Drupal\Core\StackMiddleware\Session->handle() (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 28)
Drupal\Core\StackMiddleware\ContentLength->handle() (Line: 53)
Asm89\Stack\Cors->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 36)
Drupal\Core\StackMiddleware\AjaxPageState->handle() (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle() (Line: 741)
Drupal\Core\DrupalKernel->handle() (Line: 19)

Warning: Undefined array key 1 in Drupal\Core\Asset\LibraryDependencyResolver->doGetDependencies() (line 67 of core/lib/Drupal/Core/Asset/LibraryDependencyResolver.php).

Drupal\Core\Asset\LibraryDependencyResolver->doGetDependencies() (Line: 70)
Drupal\Core\Asset\LibraryDependencyResolver->doGetDependencies() (Line: 70)
Drupal\Core\Asset\LibraryDependencyResolver->doGetDependencies() (Line: 41)
Drupal\Core\Asset\LibraryDependencyResolver->getLibrariesWithDependencies() (Line: 116)
Drupal\Core\Asset\AssetResolver->getLibrariesToLoad() (Line: 175)
Drupal\Core\Asset\AssetResolver->getCssAssets() (Line: 323)
Drupal\Core\Render\HtmlResponseAttachmentsProcessor->processAssetLibraries() (Line: 167)
Drupal\Core\Render\HtmlResponseAttachmentsProcessor->processAttachments() (Line: 45)
Drupal\Core\EventSubscriber\HtmlResponseSubscriber->onRespond()
call_user_func() (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch() (Line: 214)
Symfony\Component\HttpKernel\HttpKernel->filterResponse() (Line: 202)
Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 76)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 53)
Drupal\Core\StackMiddleware\Session->handle() (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 28)
Drupal\Core\StackMiddleware\ContentLength->handle() (Line: 53)
Asm89\Stack\Cors->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 36)
Drupal\Core\StackMiddleware\AjaxPageState->handle() (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle() (Line: 741)
Drupal\Core\DrupalKernel->handle() (Line: 19)