code: private function checkConfig(): void
      {
          if (empty($this->userkey)) {
              Log::warning('Config "message.zenziva.userkey" is not defined.');
          }
  
          if (empty($this->passkey)) {
              Log::warning('Config "message.zenziva.passkey" is not defined.');
          }
      }
docs: Check config and add to log for easy debugging.
  
  @return void