conf: ensure that "hidden" features actually exist during validation

rust2rpm/conf.py

@@ -468,6 +468,10 @@ class TomlConf:
                 for enabled in enable_list:
                     if enabled not in features:
                         raise ConfError(f'Unrecognized "enabled" feature: {enabled!r}')
+            if hide_list := features_list.get("hide"):
+                for hidden in hide_list:
+                    if hidden not in features:
+                        raise ConfError(f'Unrecognized "hidden" feature: {hidden!r}')
 
         if requires_table := toml.get("requires"):
             if features_list := requires_table.get("features"):

rust2rpm/tests/test_conf.py

@@ -92,7 +92,7 @@ def test_ini_conf_load(
         ),
         (
             "chrono-0.4.23.rust2rpm.toml",
-            set(),
+            {"__doctest"},
             TomlConf(
                 {
                     "features": {