Notice: Undefined index: alt in includes\skins\Skin.php on line 1007

When

$wgRightsUrl  = "";
$wgRightsText = "";
$wgRightsIcon = "";

It seems that the $wgFooterIcons get an empty array and that is formatted in Skin::makeFooterIcon, but it fails.
I have no idea if the footer icons should be clean up when there is an empty array or if some other places should skip it.

I am not sure if this is a regression for release 1.35, but BaseTemplate::getFooterIcons was deprecated in 1.35