Redirect to originally requested url after login does not work

When I navigate to a particular resource on a schleuder-web interface with no pre-existing session, then I am not properly redirected to that url after login.

Steps to reproduce

1. open an incognito window
2. visit some-schleuder-web/lists/some_list
3. login
4. it wrongly redirects to / instead of /lists/some_list
5. logout
6. visit some-schleuder-web/lists/some_list again
7. login
8. it correctly redirects to /lists/some_list

Potential Fix

I am pretty sure the error is at https://0xacab.org/schleuder/schleuder-web/-/blob/master/app/controllers/application_controller.rb#L87 as I get the following error in the logs: Error: no implicit conversion of nil into String.

I would suggest a fix along these lines:

   def authenticate
-    expiry = Time.parse(session[:login_expires_at])
-    if current_account && expiry > Time.now
+    expiry = Time.parse("#{session[:login_expires_at]}") rescue nil
+    if current_account && expiry && expiry > Time.now
       update_session_expiry

However, what seems to be an additional issue is that the message at https://0xacab.org/schleuder/schleuder-web/-/blob/master/app/controllers/application_controller.rb#L110 is never displayed in the login form. The login form always says "please log in with your schleuder account" and does not display the error.