Not working

@erwangel
Try to add one more condition in user_menu_avatar.module to fix the issue,
if (uma_anon_markup() && is_object($menu_link['url']) && $menu_link['url']->isRouted() && $menu_link['url']->getRouteName() === "user.login") {

Still not working. With the suggested changes I was able to access the settings page but once I validated the form I got again a wsod and was logged out with a RuntimeException: Failed to start the session. in Symfony\Component\HttpFoundation\Session\Storage\NativeSessionStorage->start() (line 173 of /path_to_site_root/vendor/symfony/http-foundation/Session/Storage/NativeSessionStorage.php).
Cache rebuild didn't help, it just permit access to the login page but once the credentials validated, white scren again. I had to uninstall the module to get the site back.
In the php logs Maximum execution time of 40 seconds exceeded and Allowed memory size exhausted as well as Warning: session_start(): Failed to decode session object. Session has been destroyed in Drupal logs which just explains the symphony session failure.

Here a patch that try to fix the issue adding some checks