make CI happy

Author: LiuYuHui

mypy/checker.py

@@ -947,7 +947,8 @@ def check_func_def(self, defn: FuncItem, typ: CallableType, name: Optional[str])
                             if ctx.line < 0:
                                 ctx = typ
                             self.fail(message_registry.FUNCTION_PARAMETER_CANNOT_BE_COVARIANT, ctx)
-                    elif (is_named_instance(arg_type, 'builtins.list')
+                    elif (isinstance(arg_type, Instance)
+                            and is_named_instance(arg_type, 'builtins.list')
                             and isinstance(self.iterable_item_type(arg_type), TypeVarType)):
                         if(self.iterable_item_type(arg_type).variance == COVARIANT):
                             message = "Cannot use a covariant type variable as a parameter"