count_twittersが未定義というエラー

Undefined variable: count_twitters (View: /home/ec2-user/environment/twitter-clone/resources/views/users/show.blade.php)
上記のエラーが出たのですが、自分では原因が見つけれていないので質問させて頂きます。
Twitterのクローンサイトを作りたくて、まずは教科書から真似てコードを書いています。

お手数おかけしますが、ご教示お願いします。

show.blade.php

@extends('layouts.app')

@section('content')
    <div class="row">
        <aside class="col-xs-4">
            <div class="panel panel-default">
                <div class="panel-heading">
                    <h3 class="panel-title">{{ $user->name }}</h3>
                </div>
                <div class="panel-body">
                    <img class="media-object img-rounded img-responsive" src="{{ Gravatar::src($user->email, 500) }}" alt="">
                </div>
            </div>
            @include('user_follow.follow_button', ['user' => $user])
        </aside>
        <div class="col-xs-8">
            <ul class="nav nav-tabs nav-justified">
                <li role="presentation" class="{{ Request::is('users/' . $user->id) ? 'active' : '' }}"><a href="{{ route('users.show', ['id' => $user->id]) }}">TimeLine <span class="badge">{{ $count_twitters }}</span></a></li>
                <li role="presentation" class="{{ Request::is('users/*/followings') ? 'active' : '' }}"><a href="{{ route('users.followings', ['id' => $user->id]) }}">Followings <span class="badge">{{ $count_followings }}</span></a></li>
                <li role="presentation" class="{{ Request::is('users/*/followers') ? 'active' : '' }}"><a href="{{ route('users.followers', ['id' => $user->id]) }}">Followers <span class="badge">{{ $count_followers }}</span></a></li>
            </ul>
            @if (Auth::id() == $user->id)
                  {!! Form::open(['route' => 'twitters.store']) !!}
                      <div class="form-group">
                          {!! Form::textarea('content', old('content'), ['class' => 'form-control', 'rows' => '2']) !!}
                          {!! Form::submit('Post', ['class' => 'btn btn-primary btn-block']) !!}
                      </div>
                  {!! Form::close() !!}
            @endif
            @if (count($twitters) > 0)
                @include('twitters.twitters', ['twitters' => $twitters])
            @endif
        </div>
    </div>
@endsection

Controller.php

<?php

namespace App\Http\Controllers;

use Illuminate\Foundation\Bus\DispatchesJobs;
use Illuminate\Routing\Controller as BaseController;
use Illuminate\Foundation\Validation\ValidatesRequests;
use Illuminate\Foundation\Auth\Access\AuthorizesRequests;

use App\User; 
use App\Twitter;

class Controller extends BaseController
{
    use AuthorizesRequests, DispatchesJobs, ValidatesRequests;

    public function counts($user) {
        $count_twitters = $user->twitters()->count();
        $count_followings = $user->followings()->count();
        $count_followers = $user->followers()->count();

        return [
            'count_twitters' => $count_twitters,
            'count_followings' => $count_followings,
            'count_followers' => $count_followers,
        ];
    }
}

UsersController.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;

use App\User;
use App\Twitter;

class UsersController extends Controller
{

    public function index()
    {
        $users = User::paginate(10);

        return view('users.index', [
            'users' => $users,
        ]);


    }
    public function show($id)
    {
        $user = User::find($id);
        $twitters = $user->twitters()->orderBy('created_at', 'desc')->paginate(10);

        $data = [
            'user' => $user,
            'twitters' => $twitters,
        ];

        $data += $this->counts($user);

        return view('users.show', $data);

    }
    public function followings($id)
    {
        $user = User::find($id);

        return view('users.show', [
            'user' => $user,
        ]);
    }

    public function followers($id)
    {
        $user = User::find($id);
        $followers = $user->followers()->paginate(10);

        $data = [
            'user' => $user,
            'users' => $followers,
        ];

        $data += $this->counts($user);

        return view('users.followers', $data);
    }

}