public function login(Request $request) {

    $inputted_orderId = $request->input('order_id');
    $orderIdInDB = DB::table(self::SITE_IN_DEVELOPMENT_TABLE_NAME)
            ->where(self::ORDER_ID_FIELD_NAME, $inputted_orderId)->first();

   if (is_null($orderIdInDB)) {
       return Redirect::route('loginToSitesInDevelopmentZonePage')->withErrors('wrongOrderId');
   }
}

@if (!empty($errors->first('wrongOrderId')))
    <div class="signInForm-errorMessagebox" id="invalidID-errorMessage">
        <!-- ... -->
    </div>
@endif

@if($errors->any())
    <div class="signInForm-errorMessagebox" id="invalidID-errorMessage">
        <!-- ... -->
    </div>
 @endif