Getting errors in browser but not in terminal on ubuntu 14.04 LTS PHP 7.1.8

I've upgraded PHP version form 5.6 to PHP 7.1.8

I've installed http://ift.tt/1TvEIIC with composer and get installed GeocoderLaravel 4 in Laravel 5.4.32

When I run my project after php artisan serve then it works fine on served URL: http://ift.tt/1nHH4WY

But when i browse my virtual host i get error syntax error, unexpected ':', expecting ';' or '{'

for this code:

protected function callback() : string
{
}

protected function callback() : array
{
}

$this->decider = $decider ?? __CLASS__.'::getProvider';

unexpected ? etc...

via Chebli Mohamed