Depricated: getCredentials should not return null

[ottaviano]

php.INFO: User Deprecated: Returning null from "EnMarche\OAuthClient\OAuthAuthenticator::getCredentials()" is deprecated since Symfony 3.4 and will throw an \UnexpectedValueException in 4.0. Return false from "EnMarche\OAuthClient\OAuthAuthenticator::supports()" instead. {"exception":"[object] (ErrorException(code: 0): User Deprecated: Returning null from \"EnMarche\\OAuthClient\\OAuthAuthenticator::getCredentials()\" is deprecated since Symfony 3.4 and will throw an \\UnexpectedValueException in 4.0. Return false from \"EnMarche\\OAuthClient\\OAuthAuthenticator::supports()\" instead. at /app/vendor/symfony/security/Guard/Firewall/GuardAuthenticationListener.php:127)"}