Cannot use object of type stdClass as array MailchimpListsSubscribeForm->buildForm()

The form builder for MailchimpListsSubscribeForm expects an array from mailchimp_get_list(), and is real sad when it gets an object.

 Error: Cannot use object of type stdClass as array in Drupal\mailchimp_lists\Form\MailchimpListsSubscribeForm->buildForm() (line 83 of 
               /var/www/drupal/public_html/web/modules/contrib/mailchimp/modules/mailchimp_lists/src/Form/MailchimpListsSubscribeForm.php) #0         
               [internal function]: Drupal\mailchimp_lists\Form\MailchimpListsSubscribeForm->buildForm(Array, Object(Drupal\Core\Form\FormState))     
               #1 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Form/FormBuilder.php(514): call_user_func_array(Array, Array)                  
               #2 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Form/FormBuilder.php(271):                                                     
               Drupal\Core\Form\FormBuilder->retrieveForm('mailchimp_lists...', Object(Drupal\Core\Form\FormState))                                   
               #3 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Form/FormBuilder.php(212):                                                     
               Drupal\Core\Form\FormBuilder->buildForm('mailchimp_lists...', Object(Drupal\Core\Form\FormState))                                      
               #4                                                                                                                                     
               /var/www/drupal/public_html/web/modules/contrib/mailchimp/modules/mailchimp_lists/src/Plugin/Field/FieldFormatter/MailchimpListsFieldS 
               ubscribeFormatter.php(90): Drupal\Core\Form\FormBuilder->getForm(Object(Drupal\mailchimp_lists\Form\MailchimpListsSubscribeForm))      
               #5 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Field/FormatterBase.php(80):                                                   
               Drupal\mailchimp_lists\Plugin\Field\FieldFormatter\MailchimpListsFieldSubscribeFormatter->viewElements(Object(Drupal\Core\Field\FieldI 
               temList), 'en')                                                                                                                        
               #6 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Entity/Entity/EntityViewDisplay.php(259):                                      
               Drupal\Core\Field\FormatterBase->view(Object(Drupal\Core\Field\FieldItemList), 'en')                                                   
               #7 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Entity/EntityViewBuilder.php(320):                                             
               Drupal\Core\Entity\Entity\EntityViewDisplay->buildMultiple(Array)                                                                      
               #8 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Entity/EntityViewBuilder.php(263):                                             
               Drupal\Core\Entity\EntityViewBuilder->buildComponents(Array, Array, Array, 'full')                                                     
               #9 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Entity/EntityViewBuilder.php(220):                                             
               Drupal\Core\Entity\EntityViewBuilder->buildMultiple(Array)                                                                             
               #10 [internal function]: Drupal\Core\Entity\EntityViewBuilder->build(Array)                                                            
               #11 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Render/Renderer.php(378): call_user_func(Array, Array)                        
               #12 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Render/Renderer.php(195): Drupal\Core\Render\Renderer->doRender(Array, false) 
               #13 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(226):                                     
               Drupal\Core\Render\Renderer->render(Array, false)                                                                                      
               #14 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Render/Renderer.php(576):                                                     
               Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}()                                                
               #15 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(227):                                     
               Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure))                         
               #16 /var/www/drupal/public_html/web/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(117):                                     
               Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array, Object(Symfony\Component\HttpFoundation\Request),                          
               Object(Drupal\Core\Routing\CurrentRouteMatch))                                                                                         
               #17 /var/www/drupal/public_html/web/core/lib/Drupal/Core/EventSubscriber/MainContentViewSubscriber.php(90):                            
               Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object(Symfony\Component\HttpFoundation\Request),                   
               Object(Drupal\Core\Routing\CurrentRouteMatch))                                                                                         
               #18 /var/www/drupal/public_html/web/core/lib/Drupal/Component/EventDispatcher/ContainerAwareEventDispatcher.php(108):                  
               Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object(Symfony\Component\HttpKernel\Event\GetResponseForContr 
               ollerResultEvent), 'kernel.view', Object(Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher))                              
               #19 /var/www/drupal/public_html/vendor/symfony/http-kernel/HttpKernel.php(158):                                                        
               Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('kernel.view',                                                
               Object(Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent))                                                        
               #20 /var/www/drupal/public_html/vendor/symfony/http-kernel/HttpKernel.php(68):                                                         
               Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)                                
               #21 /var/www/drupal/public_html/web/core/lib/Drupal/Core/StackMiddleware/Session.php(57):                                              
               Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)                             
               #22 /var/www/drupal/public_html/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(47):                                      
               Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)                                 
               #23 /var/www/drupal/public_html/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(99):                                     
               Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)                         
               #24 /var/www/drupal/public_html/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(78):                                     
               Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true)                           
               #25 /var/www/drupal/public_html/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(47):                               
               Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)                         
               #26 /var/www/drupal/public_html/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(50):                                
               Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)                  
               #27 /var/www/drupal/public_html/vendor/stack/builder/src/Stack/StackedHttpKernel.php(23):                                              
               Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)                   
               #28 /var/www/drupal/public_html/web/core/lib/Drupal/Core/DrupalKernel.php(657):                                                        
               Stack\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)                                             
               #29 /var/www/drupal/public_html/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))  
               #30 {main}.