I'm trying to make an email verification system by I keep getting an error "Undefined variable: code"

Question

I'm making a verification system using laravel8. The system works fine and it allows a user (me) to register. After registration, an email is sent to the user with a verification link. Now, the problem occurs when the user clicks the link. An error "Undefined variable: code". Here's the error and the code enter image description here

ActivateAccountController <?php

  namespace App\Http\Controllers;
  use App\Models\User;
  use Illuminate\Http\Request;
  use App\Mail\ActivateYourAccount;
  use Illuminate\Support\Facades\Mail;

  class ActivateAccountController extends Controller
 {
//
public function activation(){
    $user = User::where('code',$code)->first();
    $user->code = null;
    $user->update([
        'active' => 1
    ]);
    auth()->login($user);
    return redirect('/')->withSuccess('Connected');
    }

    public function resendCode($email){
    $user = User::where('email',$email)->first();
    if($user->active){
        return redirect('/');
    }
    Mail::to($user)->send(new ActivateYourAccount($user->code));
    return redirect('/login')->withSuccess('The link was sent to your email address');
   }
   }

Can anyone assist me with a solution to the problem which appears on line13

$user = User::where('code',$code)->first();