FIX: Don't raise error when admin access is invalid.

lib/admin_constraint.rb

@@ -10,6 +10,8 @@ class AdminConstraint
     return false if @require_master && RailsMultisite::ConnectionManagement.current_db != "default"
     provider = Discourse.current_user_provider.new(request.env)
     provider.current_user && provider.current_user.admin?
+  rescue Discourse::InvalidAccess
+    false
   end
 
 end