Handle not-existing preferences

aleksis/apps/ldap/util/ldap_sync.py

@@ -220,7 +220,11 @@ def ldap_sync_from_user(user, dn, attrs):
         setting_name = "ldap__" + setting_name_from_field(Person, field)
 
         # Try sync if constance setting for this field is non-empty
-        ldap_field = get_site_preferences()[setting_name].lower()
+        try:
+            ldap_field = get_site_preferences()[setting_name].lower()
+        except Exception:
+            ldap_field = None
+
         if ldap_field and ldap_field in attrs:
             value = attrs[ldap_field][0]