fozen_box with lists cannot converted to YAML

[Eusebius1920]

Bug

Simple example

from box import Box

test_box = Box({'a': [{'b': 123}, {'b': 222}]}, frozen_box=True)
test_box.to_yaml()

This yields the following error:

ruamel.yaml.representer.RepresenterError: cannot represent an object: {'b': 123}

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "box/box.py", line 1013, in box.box.Box.to_yaml
  File "box/converters.py", line 207, in box.converters._to_yaml
  File "box/converters.py", line 208, in box.converters._to_yaml
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/main.py", line 594, in dump
    return self.dump_all([data], stream, transform=transform)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/main.py", line 604, in dump_all
    self._context_manager.dump(data)
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/main.py", line 953, in dump
    self._yaml.representer.represent(data)
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/representer.py", line 83, in represent
    node = self.represent_data(data)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/representer.py", line 105, in represent_data
    node = self.yaml_representers[data_types[0]](self, data)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/representer.py", line 318, in represent_dict
    return self.represent_mapping('tag:yaml.org,2002:map', data)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/representer.py", line 841, in represent_mapping
    node_value = self.represent_data(item_value)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/representer.py", line 105, in represent_data
    node = self.yaml_representers[data_types[0]](self, data)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/representer.py", line 309, in represent_list
    return self.represent_sequence('tag:yaml.org,2002:seq', data)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/representer.py", line 750, in represent_sequence
    node_item = self.represent_data(item)
                ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/representer.py", line 115, in represent_data
    node = self.yaml_representers[None](self, data)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/daniel/.local/share/virtualenvs/bedrock-JuU-uWSt/lib/python3.11/site-packages/ruamel/yaml/representer.py", line 347, in represent_undefined
    raise RepresenterError(f'cannot represent an object: {data!s}')
ruamel.yaml.representer.RepresenterError: cannot represent an object: {'b': 123}

Investigation

The problem is that - when using frozen_box=True - that lists get converted to tuples. But then test_box.to_dict() does not remove the Boxes from tuples so we have this:

test_box.to_dict()
# {'a': (Box({'b': 123}), Box({'b': 222}))}

which should actually be this:

test_box.to_dict()
# {'a': ({'b': 123}, {'b': 222})}