Custom exception to break out of AJAX form processing. Hierarchy class \Drupal\Core\Form\

public FormBuilder::executeSubmitHandlers(&$form, FormStateInterface &a

public EnforcedResponseException::getResponse()

public FormStateDecoratorBase::setProgrammed($programmed

public FormStateInterface::getCacheableArray()

Handles form errors. Hierarchy class \Drupal\Core\Form\

public FormState::getError(array $element) Returns

public FormStateDecoratorBase::prepareCallback($callback)

public FormState::isValidationEnforced() Checks

public FormStateInterface::getRedirect()