I encountered the following error testing Subscription billing with Commerce recurring on drupal 8. The error happens at checkout, I added a custom field to contain 'billing schedule' on the user form in the line item. I think it stays empty (null). The field is reference to entity billing schedule.
I have no idea what is going wrong, this worked ok when first installed I believe. Any suggestions?
Error: Call to a member function getPlugin() on null in Drupal\commerce_recurring\EventSubscriber\OrderSubscriber->onPlace() (regel 90 van /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/modules/commerce_recurring/src/EventSubscriber/OrderSubscriber.php) #0 [internal function]: Drupal\commerce_recurring\EventSubscriber\OrderSubscriber->onPlace(Object(Drupal\state_machine\Event\WorkflowTransitionEvent), 'commerce_order....', Object(Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher)) #1 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Component/EventDispatcher/ContainerAwareEventDispatcher.php(111): call_user_func(Array, Object(Drupal\state_machine\Event\WorkflowTransitionEvent), 'commerce_order....', Object(Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher)) #2 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/modules/contrib/state_machine/src/Plugin/Field/FieldType/StateItem.php(361): Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('commerce_order....', Object(Drupal\state_machine\Event\WorkflowTransitionEvent)) #3 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/modules/contrib/state_machine/src/Plugin/Field/FieldType/StateItem.php(322): Drupal\state_machine\Plugin\Field\FieldType\StateItem->dispatchTransitionEvent('pre_transition') #4 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Field/FieldItemList.php(233): Drupal\state_machine\Plugin\Field\FieldType\StateItem->preSave() #5 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Field/FieldItemList.php(191): Drupal\Core\Field\FieldItemList->delegateMethod('preSave') #6 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php(873): Drupal\Core\Field\FieldItemList->preSave() #7 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php(823): Drupal\Core\Entity\ContentEntityStorageBase->invokeFieldMethod('preSave', Object(Drupal\commerce_order\Entity\Order)) #8 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/modules/contrib/commerce/src/CommerceContentEntityStorage.php(100): Drupal\Core\Entity\ContentEntityStorageBase->invokeHook('presave', Object(Drupal\commerce_order\Entity\Order)) #9 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/modules/contrib/commerce/modules/order/src/OrderStorage.php(111): Drupal\commerce\CommerceContentEntityStorage->invokeHook('presave', Object(Drupal\commerce_order\Entity\Order)) #10 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Entity/EntityStorageBase.php(500): Drupal\commerce_order\OrderStorage->invokeHook('presave', Object(Drupal\commerce_order\Entity\Order)) #11 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php(692): Drupal\Core\Entity\EntityStorageBase->doPreSave(Object(Drupal\commerce_order\Entity\Order)) #12 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Entity/EntityStorageBase.php(454): Drupal\Core\Entity\ContentEntityStorageBase->doPreSave(Object(Drupal\commerce_order\Entity\Order)) #13 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php(838): Drupal\Core\Entity\EntityStorageBase->save(Object(Drupal\commerce_order\Entity\Order)) #14 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Entity/EntityBase.php(394): Drupal\Core\Entity\Sql\SqlContentEntityStorage->save(Object(Drupal\commerce_order\Entity\Order)) #15 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/modules/contrib/commerce/modules/checkout/src/Plugin/Commerce/CheckoutFlow/CheckoutFlowBase.php(139): Drupal\Core\Entity\EntityBase->save() #16 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/modules/contrib/commerce/modules/payment/src/Plugin/Commerce/CheckoutPane/PaymentProcess.php(180): Drupal\commerce_checkout\Plugin\Commerce\CheckoutFlow\CheckoutFlowBase->redirectToStep('complete') #17 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/modules/contrib/commerce/modules/checkout/src/Plugin/Commerce/CheckoutFlow/CheckoutFlowWithPanesBase.php(559): Drupal\commerce_payment\Plugin\Commerce\CheckoutPane\PaymentProcess->buildPaneForm(Array, Object(Drupal\Core\Form\FormState), Array) #18 [internal function]: Drupal\commerce_checkout\Plugin\Commerce\CheckoutFlow\CheckoutFlowWithPanesBase->buildForm(Array, Object(Drupal\Core\Form\FormState), 'payment') #19 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Form/FormBuilder.php(519): call_user_func_array(Array, Array) #20 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Form/FormBuilder.php(276): Drupal\Core\Form\FormBuilder->retrieveForm('commerce_checko...', Object(Drupal\Core\Form\FormState)) #21 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Form/FormBuilder.php(217): Drupal\Core\Form\FormBuilder->buildForm(Object(Drupal\commerce_checkout\Plugin\Commerce\CheckoutFlow\MultistepDefault), Object(Drupal\Core\Form\FormState)) #22 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/modules/contrib/commerce/modules/checkout/src/Controller/CheckoutController.php(94): Drupal\Core\Form\FormBuilder->getForm(Object(Drupal\commerce_checkout\Plugin\Commerce\CheckoutFlow\MultistepDefault), 'payment') #23 [internal function]: Drupal\commerce_checkout\Controller\CheckoutController->formPage(Object(Drupal\Core\Routing\RouteMatch)) #24 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array(Array, Array) #25 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/Render/Renderer.php(582): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() #26 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(124): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure)) #27 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) #28 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/vendor/symfony/http-kernel/HttpKernel.php(151): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() #29 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/vendor/symfony/http-kernel/HttpKernel.php(68): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1) #30 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/StackMiddleware/Session.php(57): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #31 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(47): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #32 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(106): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #33 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(85): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true) #34 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/modules/ban/src/BanMiddleware.php(50): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #35 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(47): Drupal\ban\BanMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #36 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(52): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #37 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/vendor/stack/builder/src/Stack/StackedHttpKernel.php(23): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #38 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/core/lib/Drupal/Core/DrupalKernel.php(693): Stack\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #39 /data/sites/web/myassistbe/subsites/d8.als.myassist.be/d8als/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request)) #40 {main}./code>