While giving an command in shell "php artisan app:install" its throwing an error

PHP Warning: require(/var/www/html/snipeit/bootstrap/../vendor/autoload.php): failed to open stream: No such file or directory in /var/www/html/snipeit/bootstrap/autoload.php on line 17
PHP Fatal error: require(): Failed opening required '/var/www/html/snipeit/bootstrap/../vendor/autoload.php' (include_path='.:/usr/share/pear:/usr/share/php') in /var/www/html/snipeit/bootstrap/autoload.php on line 17

While giving an command in shell "php artisan app:install" its throwing an error

PHP Warning: require(/var/www/html/snipeit/bootstrap/../vendor/autoload.php): failed to open stream: No such file or directory in /var/www/html/snipeit/bootstrap/autoload.php on line 17
PHP Fatal error: require(): Failed opening required '/var/www/html/snipeit/bootstrap/../vendor/autoload.php' (include_path='.:/usr/share/pear:/usr/share/php') in /var/www/html/snipeit/bootstrap/autoload.php on line 17

Hello Team,

i'm facing the below issue while open the http://localhost/ with my ip address

**
Error **

Error in exception handler: The stream or file "/var/www/html/snipeit/app/storage/logs/log-apache2handler-2015-12-19.txt" could not be opened: failed to open stream: Permission denied in /var/www/html/snipeit/vendor/monolog/monolog/src/Monolog/Handler/StreamHandler.php:87

Kindly let me know how to fix the issue,

Thanks Team,
Golden John S