Laravel 5.8: syntax error, unexpected '=>' (T_DOUBLE_ARROW), expecting ',' or ')'

[naowas]

Unable to hit route www.domain.com/health/check or artisan command health:panel

Issue occurring on \vendor\pragmarx\health\src\Checkers\Extensions.php

$alerts = $needed->reject(fn ($value) => $installed->contains($value));

Laravel version: 5.8
PHP: 7.2.3

[lintaba]

fn (arrow functions ) are introduced in PHP 7.4.
Either the composers.json's minimum php version should be bumped to 7.4, or it should be replaced with the long version. I'd vote for the second option, so made a PR: #265