Call to a member function addClass() on array in claro_preprocess_form_element when calling page admin/modules

I am not get this type of issue on this version. Please check it once again.

I'm getting this error, too, and it's quite annoying. I can't do anything unless I hack the `claro.theme` file. Even when the 'Proposed Solution' is done, I'm getting this error that appears to be related, except my error says 'null' instead of 'array':

Error: Call to a member function addClass() on null in claro_preprocess_links__action_links() (line 1245 of core/themes/claro/claro.theme).

call_user_func_array('claro_preprocess_links__action_links', Array) (Line: 285)
Drupal\Core\Theme\ThemeManager->render('links__action_links', Array) (Line: 445)
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: 194)
__TwigTemplate_10df5664077d83d1951875e752383543->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/gin/templates/system/system-themes-page.html.twig', Array) (Line: 372)
Drupal\Core\Theme\ThemeManager->render('system_themes_page', Array) (Line: 445)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 458)
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: 592)
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: 187)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 76)
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)

I created a patch that checks to see if the `attributes` key exists before invoking `addClass`, but this feels like there's something else that has gone awry...

Added the issue template but there are sections that need to be filled in, mainly steps to reproduce and an agreed solution.

Will need a test case also.

@johnnydarkko, Normally going to /admin/modules (as said in the issue summary) is not making any errors. Maybe some custom/contributed module's links are generating the problem. Try to recreate the problem by disabling all non-core installed modules.

Attempted to replicate the issue on versions 10.1.x and 11.0.x by introducing the German language and exploring various pages, including /admin/modules. However, I was unable to encounter the error. @nivethitha, it would be appreciated if you could provide instructions on how to reproduce this issue. Thank you.

Turns out the issue was due to some bad custom code in a custom module overriding link text in an implementation of hook_preprocess_links for a link that doesn't exist in the variables array of the admin pages that were whitescreening for me. So, the case I described earlier isn't a valid report, but I'll leave this all here just in case it helps someone else making the same bonehead mistake :)

Not deleting the issue just moving to a different bucket.