title: Call to a member function lists() on null in laravel 5.3
body: <p>In laravel 5.3, I am trying to edit registered users in the All Users page (admin/users) and assign roles and permissions to them. I used the codes from laravel 5.2 pdf book. but anytime i click on a user to edit it. It brings up below error</p>
  
  <blockquote>
    <p>FatalThrowableError in UsersController.php line 26: Call to a member
    function lists() on null.</p>
  </blockquote>
  
  <pre><code>public function edit($id)
  {
      $user = User::whereId($id)-&gt;firstOrFail();
      $roles = Role::all();
      $selectedRoles = $user-&gt;roles-&gt;lists('id')-&gt;toArray();
      return view('backend.users.edit', compact('user', 'roles', 'selectedRoles'));
  }
  </code></pre>