Fix two errors, one logical and one type

Author: tleonhardt

cmd2/argparse_completer.py

@@ -357,7 +357,7 @@ def consume_argument(arg_state: _ArgumentState, arg_token: str) -> None:
                     action = remaining_positionals.popleft()
 
                     # Are we at a subcommand? If so, forward to the matching completer
-                    if action == self._subcommand_action:
+                    if self._subcommand_action is not None and action == self._subcommand_action:
                         if token in self._subcommand_action.choices:
                             # Merge self._parent_tokens and consumed_arg_values
                             parent_tokens = {**self._parent_tokens, **consumed_arg_values}

cmd2/utils.py

@@ -74,7 +74,7 @@ def __init__(
         settable_object: object,
         *,
         settable_attrib_name: str | None = None,
-        onchange_cb: Callable[[str, _T, _T], Any] | None = None,
+        onchange_cb: Callable[[str, Any, Any], Any] | None = None,
         choices: Iterable[Any] | None = None,
         choices_provider: ChoicesProviderUnbound[CmdOrSet] | None = None,
         completer: CompleterUnbound[CmdOrSet] | None = None,