Laravel : "Call to undefined method Illuminate\Http\RedirectResponse::total()"

I'm trying to redirect users if the parameter for getRecipiantAndSamplesAll is equal to null, it keeps giving me this error:

"Call to undefined method Illuminate\Http\RedirectResponse::total()"

My code looks like this. Can anyone tell me what this error means?

Page Controller:

namespace App\Http\Controllers\Front;

use App\Http\Controllers\Controller;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Auth;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Session;
use Illuminate\Http\RedirectResponse;

/**
     * @param $pd_id
     * @return \Illuminate\Contracts\Pagination\LengthAwarePaginator
     */
    public function getRecipiantAndSamplesAll($pd_id)
    {
        if($pd_id == null){
            return redirect()->route('login');
        }
        else {
            // something else happens  
        }
    }

Web.php:

Route::get('login', 'Front\AuthController@loginForm')->name('login-form');

AuthController:

/**
     * Show login form
     */
    public function loginForm()
    {
        if (Auth::check()) {
            return redirect()->action('HomeController@index');
        } else {
            return view('auth.account-login');
        }
    }

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