title: I get BadMethodCallException Call to undefined method App\Models\User::identifiableAttribute()
body: <p>I get this error after clicking 'New Post' button the frontend of the app:<br />
  Posts view<br />
  <a href="https://i.stack.imgur.com/EAuyS.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EAuyS.jpg" alt="enter image description here" /></a></p>
  <p>Line from my log file:<br />
  <em>[2020-09-27 14:41:03] local.ERROR: Call to undefined method App\Models\User::identifiableAttribute() {&quot;exception&quot;:&quot;[object] (BadMethodCallException(code: 0): Call to undefined method App\Models\User::identifiableAttribute() at C:\xampp\htdocs\backpack-demo\vendor\laravel\framework\src\Illuminate\Support\Traits\ForwardsCalls.php:50)</em></p>
  <p>I am using Laravel 7 + Backpack CRDU generator</p>
  <p><strong>Posts Controller:</strong></p>
  <pre><code>&lt;?php
  
  namespace App\Http\Controllers;
  
  use App\Events\NewPost;
  use App\Http\Requests\PostStoreRequest;
  use App\Jobs\SyncMedia;
  use App\Mail\ReviewPost;
  use App\Models\Post;
  use Illuminate\Http\Request;
  use Illuminate\Support\Facades\Mail;
  
  class PostController extends Controller
  {
      /**
       * @param \Illuminate\Http\Request $request
       * @return \Illuminate\Contracts\Foundation\Application|\Illuminate\Contracts\View\Factory|\Illuminate\View\View
       */
      public function index(Request $request)
      {
          $posts = Post::all();
  
          return view('post.index', compact('posts'));
      }
  
      /**
       * @param \App\Http\Requests\PostStoreRequest $request
       * @return \Illuminate\Http\RedirectResponse
       */
      public function store(PostStoreRequest $request)
      {
          $post = Post::create($request-&gt;validated());
  
          Mail::to($post-&gt;author-&gt;email)-&gt;send(new ReviewPost($post));
  
          SyncMedia::dispatch($post);
  
          event(new NewPost($post));
  
          $request-&gt;session()-&gt;flash('post.title', $post-&gt;title);
  
          return redirect()-&gt;route('post.index');
      }
  }
  </code></pre>
  <p><strong>Posts Model:</strong></p>
  <pre><code> class Post extends Model
      {
          use CrudTrait;
          /**
           * The attributes that are mass assignable.
           *
           * @var array
           */
          protected $fillable = [
              'title',
              'content',
              'published_at',
              'author_id',
          ];
      
          /**
           * The attributes that should be cast to native types.
           *
           * @var array
           */
          protected $casts = [
              'id' =&gt; 'integer',
              'author_id' =&gt; 'integer',
          ];
      
          /**
           * The attributes that should be mutated to dates.
           *
           * @var array
           */
          protected $dates = [
              'published_at',
          ];
      
          public static function create(array $validated)
          {
          }
      
      
          public function author()
          {
              return $this-&gt;belongsTo(User::class);
          }
      }
  </code></pre>
  <p><strong>User model:</strong></p>
  <pre><code>class User extends Authenticatable
  {
      use Notifiable;
  
      /**
       * The attributes that are mass assignable.
       *
       * @var array
       */
      protected $fillable = [
          'name', 'email', 'password',
      ];
  
      /**
       * The attributes that should be hidden for arrays.
       *
       * @var array
       */
      protected $hidden = [
          'password', 'remember_token',
      ];
  
      /**
       * The attributes that should be cast to native types.
       *
       * @var array
       */
      protected $casts = [
          'email_verified_at' =&gt; 'datetime',
      ];
  }
  </code></pre>