schema problem during install

When trying to install the module, I got the following errors;

Drupal\Core\Config\Schema\SchemaIncompleteException: Schema errors for languageicons.settings with the following errors: languageicons.settings:_core missing schema, languageicons.settings:langcode missing schema in Drupal\Core\Config\Development\ConfigSchemaChecker->onConfigSave() (line 94 of core/lib/Drupal/Core/Config/Development/ConfigSchemaChecker.php).

Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('config.save', Object) (Line: 227)
Drupal\Core\Config\Config->save(1) (Line: 325)
Drupal\Core\Config\ConfigInstaller->createConfiguration('', Array) (Line: 125)
Drupal\Core\Config\ConfigInstaller->installDefaultConfig('module', 'languageicons') (Line: 75)
Drupal\Core\ProxyClass\Config\ConfigInstaller->installDefaultConfig('module', 'languageicons') (Line: 248)
Drupal\Core\Extension\ModuleInstaller->install(Array, 1) (Line: 83)
Drupal\Core\ProxyClass\Extension\ModuleInstaller->install(Array) (Line: 450)
Drupal\system\Form\ModulesListForm->submitForm(Array, Object)
call_user_func_array(Array, Array) (Line: 111)
Drupal\Core\Form\FormSubmitter->executeSubmitHandlers(Array, Object) (Line: 51)
Drupal\Core\Form\FormSubmitter->doSubmitForm(Array, Object) (Line: 585)
Drupal\Core\Form\FormBuilder->processForm('system_modules', Array, Object) (Line: 314)
Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 74)
Drupal\Core\Controller\FormController->getContentResult(Object, Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 574)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
call_user_func_array(Object, Array) (Line: 144)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 64)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 99)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 78)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 50)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 656)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)