laravel Call to undefined function get()
<p>when i run a command in laravel project :</p>

<pre><code> php artisan optimize                                                      

[Symfony\Component\Debug\Exception\FatalErrorException]  
Call to undefined function get()                         

Script php artisan optimize handling the post-update-cmd event returned with an error


[RuntimeException]  
Error Output:       
</code></pre>

<p>and</p>

<pre><code>php artisan clear-compiled


[Symfony\Component\Debug\Exception\FatalErrorException]  
Call to undefined function get()            
</code></pre>

<p>and </p>

<pre><code>php artisan optimize --force


[Symfony\Component\Debug\Exception\FatalErrorException]  
Call to undefined function get()  
</code></pre>

<p>and</p>

<p>{
    composer update
     Loading composer repositories with package information
    Updating dependencies (including require-dev)
     - Removing barryvdh/laravel-ide-helper (v2.1.4)
     - Removing symfony/class-loader (v3.1.0)
     Writing lock file
     Generating autoload files</p>

<blockquote>
  <p>Illuminate\Foundation\ComposerScripts::postUpdate
  php artisan optimize</p>
</blockquote>

<pre><code>[Symfony\Component\Debug\Exception\FatalErrorException]  
Call to undefined function get()                         


 Script php artisan optimize handling the post-update-cmd event returned with an error


 [RuntimeException]  
Error Output:                   
</code></pre>

<p>}</p>

<p>and my composer.json is </p>

<pre><code>{
"name": "laravel/laravel",
"description": "The Laravel Framework.",
"keywords": ["framework", "laravel"],
"license": "MIT",
"type": "project",
"require": {
    "php": "&gt;=5.5.9",
    "laravel/framework": "5.2.*",
    "laravelcollective/html": "5.2.*"
},
"require-dev": {
    "fzaninotto/faker": "~1.4",
    "mockery/mockery": "0.9.*",
    "phpunit/phpunit": "~4.0",
    "symfony/css-selector": "2.8.*|3.0.*",
    "symfony/dom-crawler": "2.8.*|3.0.*"
},
"autoload": {
    "classmap": [
        "database"
    ],
    "psr-4": {
        "App\\": "app/"
    }
},
"autoload-dev": {
    "classmap": [
        "tests/TestCase.php"
    ]
},
"scripts": {
    "post-root-package-install": [
        "php -r \"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>

<p>}</p>

<p>so, what's wrong is it,and how can i fix it? thanks?</p>