Guard _migrate validator against non-dict add-on configs (#6611)

The _migrate function in addons/validate.py is the first validator in the
SCHEMA_ADDON_CONFIG All() chain and was called directly with raw config data.
If a malformed add-on config file contained a non-dict value (e.g. a string),
config.get() would raise an AttributeError instead of a proper voluptuous
Invalid error, causing an unhandled exception.

Add an isinstance check at the top of _migrate to raise vol.Invalid for
non-dict inputs, letting validation fail gracefully.

Fixes SUPERVISOR-HMP

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

supervisor/addons/validate.py

@@ -244,6 +244,8 @@ def _migrate_addon_config(protocol=False):
     """Migrate addon config."""
 
     def _migrate(config: dict[str, Any]):
+        if not isinstance(config, dict):
+            raise vol.Invalid("Add-on config must be a dictionary!")
         name = config.get(ATTR_NAME)
         if not name:
             raise vol.Invalid("Invalid Add-on config!")

tests/addons/test_config.py

@@ -532,3 +532,12 @@ def test_ulimits_invalid_values():
     config["ulimits"] = {"nofile": {}}
     with pytest.raises(vol.Invalid):
         vd.SCHEMA_ADDON_CONFIG(config)
+
+
+def test_non_dict_config_raises_invalid():
+    """Test that a non-dict config raises vol.Invalid, not AttributeError."""
+    with pytest.raises(vol.Invalid):
+        vd.SCHEMA_ADDON_CONFIG("not a dict")
+
+    with pytest.raises(vol.Invalid):
+        vd.SCHEMA_ADDON_CONFIG(["list", "not", "dict"])