Laravel 5.3 Uploading in ubuntu16.04 nginx with command composer install --no-dev
<p>Everytime I run the command composer <code>install --no-dev</code>
I am getting this error, I am using maatwebsite in laravel as the error pointing out, I just don't know how to fix it.</p>

<blockquote>
  <p>PHP Fatal error:  Uncaught
  Symfony\Component\Debug\Exception\FatalThrowableError<br>
  : Class 'PHPExcel_Shared_Font' not found in
  /var/www/laravel/config/excel.php:18<br>
  2 Stack trace:</p>
  
  <h1>0 /var/www/laravel/vendor/laravel/framework/src/Illuminate/Foundation/Bootstrap</h1>
  
  <p>/LoadConfiguration.php(60): require()</p>
  
  <h1>1 /var/www/laravel/vendor/laravel/framework/src/Illuminate/Foundation/Bootstrap</h1>
  
  <p>/LoadConfiguration.php(38):
  Illuminate\Foundation\Bootstrap\LoadConfiguration->l<br>
  oadConfigurationFiles(Object(Illuminate\Foundation\Application),
  Object(Illumina<br>
  te\Config\Repository))</p>
  
  <h1>2 /var/www/laravel/vendor/laravel/framework/src/Illuminate/Foundation/Applicati</h1>
  
  <p>on.php(203):
  Illuminate\Foundation\Bootstrap\LoadConfiguration->bootstrap(Object<br>
  (Illuminate\Foundation\Application))</p>
  
  <h1>3 /var/www/laravel/vendor/laravel/framework/src/Illuminate/Foundation/Console/K</h1>
  
  <p>ernel.php(268):
  Illuminate\Foundation\Application->bootstrapWith(Array)</p>
  
  <h1>4 /var/www/laravel/vendor/laravel/framework/src/Illuminate/Foundation/Console/K</h1>
  
  <p>ernel.php(114): Illuminate\Foundation\Console\Kernel->boo in
  /var/www/laravel/co<br>
  nfig/excel.php on line 182 Script php artisan optimize handling the
  post-install-cmd event returned with er<br>
  ror code 255</p>
</blockquote>

<p>Update: 
This is the composer.json file content</p>

<pre><code>{
    "name": "laravel/laravel",
    "description": "The Laravel Framework.",
    "keywords": ["framework", "laravel"],
    "license": "MIT",
    "type": "project",
    "require": {
        "php": "&gt;=5.6.4",
        "laravel/framework": "5.3.*"
    },
    "require-dev": {
        "fzaninotto/faker": "~1.4",
        "mockery/mockery": "0.9.*",
        "phpunit/phpunit": "~5.0",
        "symfony/css-selector": "3.1.*",
        "symfony/dom-crawler": "3.1.*",
        "maatwebsite/excel": "~2.1.0"
    },
    "autoload": {
        "classmap": [
            "database"
        ],
        "psr-4": {
            "App\\": "app/"
        }
    },
    "autoload-dev": {
        "classmap": [
            "tests/TestCase.php"
        ]
    },
    "scripts": {
        "post-root-package-install": [
            "php -r \"file_exists('.env') || copy('.env.example', '.env');\""
        ],
        "post-create-project-cmd": [
            "php artisan key:generate"
        ],
        "post-install-cmd": [
            "Illuminate\\Foundation\\ComposerScripts::postInstall",
            "php artisan optimize"
        ],
        "post-update-cmd": [
            "Illuminate\\Foundation\\ComposerScripts::postUpdate",
            "php artisan optimize"
        ]
    },
    "config": {
        "preferred-install": "dist"
    }
}
</code></pre>