I try today to install Vistualizor on one of my servers at OVH however unsuccessfully.
and after analyse de log, i discover a bug in ostemplates_list.php on line 32.
juste change $GLOBALS["latest_os"]["lxc"] = ; by $GLOBALS["latest_os"]["lxc"] = "";
don't forget to to secure file ostemplates_list.php deletion or modification by install