remove assert

Author: algorithm1832

docs/api/gen_doc.py

@@ -412,7 +412,6 @@ def _is_self_arg(arg: ast.arg) -> bool:
         arg_list.append("*")
     for i, kwonlyarg in enumerate(fn_node.args.kwonlyargs):
         kwdefault = fn_node.args.kw_defaults[i]
-        assert kwdefault is not None
         default_value_str = _gen_default_value_string(kwdefault)
         arg_list.append(f"{kwonlyarg.arg}={default_value_str}")
     # kwarg