Laravel 5.3 project install : Script php artisan optimize handling the post-update-cmd event returned with error code 255 - php

Question

I am completely new in Laravel Framework and I am trying to install a Laravel project after cloning a project from Github. I followed all the steps mentioned in this post, but couldn't install the project.
It gets stuck every time on the "composer install" step. I get the following error which is same as when I do "composer update":
$ composer update
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 4 installs, 8 updates, 0 removals
- Updating symfony/polyfill-mbstring (v1.3.0 => v1.4.0): Loading from cache
- Updating monolog/monolog (1.22.1 => 1.23.0): Loading from cache
- Updating nikic/php-parser (v3.0.5 => v3.0.6): Loading from cache
- Updating psy/psysh (v0.8.6 => v0.8.9): Loading from cache
- Updating symfony/polyfill-util (v1.3.0 => v1.4.0): Loading from cache
- Updating symfony/polyfill-php56 (v1.3.0 => v1.4.0): Loading from cache
- Updating symfony/event-dispatcher (v3.3.0 => v3.3.4): Loading from cache
- Updating guzzlehttp/guzzle (6.2.3 => 6.3.0): Loading from cache
- Installing composer/ca-bundle (1.0.7): Loading from cache
- Installing bugsnag/bugsnag (v3.5.1): Loading from cache
- Installing bugsnag/bugsnag-psr-logger (v1.1.0): Loading from cache
- Installing bugsnag/bugsnag-laravel (v2.6.0): Loading from cache
Writing lock file
Generating autoload files
Illuminate\Foundation\ComposerScripts::postUpdate
php artisan optimize
Script php artisan optimize handling the post-update-cmd event returned with error code 255
I have no idea what It does but following some suggestions on other posts, I also tried "composer update" and "composer update" followed by "composer dumpautoload". I have no idea what is wrong with it but nothing seems to work at all. I've searched for hours everywhere but couldn't find any solution. Anyone, please help.
Here is my composer.json file:
{
"name": "laravel/laravel",
"description": "The Laravel Framework.",
"keywords": ["framework", "laravel"],
"license": "MIT",
"type": "project",
"require": {
"php": ">=5.6.4",
"laravel/framework": "5.3.*",
"intervention/image": "2.3.11",
"froala/wysiwyg-editor-php-sdk" : "*",
"chencha/share" : "^5.2",
"laravel/socialite": "^2.0",
"bugsnag/bugsnag-laravel": "^2.0"
},
"require-dev": {
"fzaninotto/faker": "~1.4",
"mockery/mockery": "0.9.*",
"symfony/css-selector": "3.1.*",
"symfony/dom-crawler": "3.1.*"
},
"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"
}
}

Answer 1

remove services.json file from bootstrap/cache folder and then run
composer dump-autoload -o