ErrorException Undefined index: message

[GrahamCampbell]

ErrorException Undefined index: message 
    /home/.../vendor/knplabs/github-api/lib/Github/HttpClient/Plugin/GithubExceptionThrower.php:77 Github\HttpClient\Plugin\GithubExceptionThrower::Github\HttpClient\Plugin\{closure}
    /home/.../vendor/php-http/httplug/src/Promise/HttpFulfilledPromise.php:34 Http\Client\Promise\HttpFulfilledPromise::then
    /home/.../vendor/knplabs/github-api/lib/Github/HttpClient/Plugin/GithubExceptionThrower.php:99 Github\HttpClient\Plugin\GithubExceptionThrower::handleRequest
    /home/.../vendor/php-http/client-common/src/PluginClient.php:161 Http\Client\Common\PluginClient::Http\Client\Common\{closure}
    ...