Portal CSS is sent with empty background when portalSkinBackground is not defined
When we want to disable portalSkinBackground, portal.css is sent with a bogus code:
html,body {
background:url("/static/common/backgrounds/") no-repeat center fixed;
background-size:cover;
}
This leads to error in web server logs:
2019/02/05 17:22:14 [error] 90151#90151: *21 directory index of "/usr/share/lemonldap-ng/portal/htdocs/static/common/backgrounds/" is forbidden, client: 81.250.130.213, server: auth.openid.club, request: "GET /static/common/backgrounds/ HTTP/1.1", host: "auth.openid.club", referrer: "https://auth.openid.club/portal.css"