class LoggingForm

class LoggingForm extends ConfigFormBase {
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'system_logging_settings';
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getEditableConfigNames() {
        return [
            'system.logging',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $config = $this->config('system.logging');
        $form['error_level'] = [
            '#type' => 'radios',
            '#title' => $this->t('Error messages to display'),
            '#default_value' => $config->get('error_level'),
            '#options' => [
                ERROR_REPORTING_HIDE => $this->t('None'),
                ERROR_REPORTING_DISPLAY_SOME => $this->t('Errors and warnings'),
                ERROR_REPORTING_DISPLAY_ALL => $this->t('All messages'),
                ERROR_REPORTING_DISPLAY_VERBOSE => $this->t('All messages, with backtrace information'),
            ],
            '#description' => $this->t('It is recommended that sites running on production environments do not display any errors.'),
        ];
        return parent::buildForm($form, $form_state);
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $this->config('system.logging')
            ->set('error_level', $form_state->getValue('error_level'))
            ->save();
        parent::submitForm($form, $form_state);
    }

}