Fix 404 on session gone

app/helpers/authentication_helper.rb

       @user_session
     else
       id = cookies.signed.permanent[:session_id] || session[:session_id]
-      @user_session ||= Session.find(id)
+      @user_session ||= Session.find_by(id: id)
     end
 
     # Edge case if a session no longer exists in the database