Error with OneToOneNullableRelation: Cannot instantiate typing.Union

[Midorina]

If you have/add a OnetoOneNullableRelation to a model, you get the following error with both aerich init-db and aerich migrate:

Traceback (most recent call last):
  File "/usr/local/bin/aerich", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.8/dist-packages/aerich/cli.py", line 257, in main
    cli()
  File "/usr/local/lib/python3.8/dist-packages/click/core.py", line 1130, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/click/core.py", line 1055, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.8/dist-packages/click/core.py", line 1654, in invoke
    super().invoke(ctx)
  File "/usr/local/lib/python3.8/dist-packages/click/core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.8/dist-packages/click/core.py", line 760, in invoke
    return __callback(*args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/click/decorators.py", line 26, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/aerich/cli.py", line 31, in wrapper
    loop.run_until_complete(f(*args, **kwargs))
  File "/usr/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "/usr/local/lib/python3.8/dist-packages/aerich/cli.py", line 70, in cli
    tortoise_config = get_tortoise_config(ctx, tortoise_orm)
  File "/usr/local/lib/python3.8/dist-packages/aerich/utils.py", line 66, in get_tortoise_config
    config_module = importlib.import_module(config_path)
  File "/usr/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 961, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 843, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/root/senran_dev/db/__init__.py", line 1, in <module>
    from .models import *
  File "/root/senran_dev/db/models.py", line 37, in <module>
    class GuildAutoNSFWConfig(BaseModel):
  File "/root/senran_dev/db/models.py", line 43, in GuildAutoNSFWConfig
    guild = fields.OneToOneNullableRelation(model_name='models.Guild')
  File "/usr/lib/python3.8/typing.py", line 729, in __call__
    result = self.__origin__(*args, **kwargs)
  File "/usr/lib/python3.8/typing.py", line 339, in __call__
    raise TypeError(f"Cannot instantiate {self!r}")
TypeError: Cannot instantiate typing.Union