Getting PointerToNowhere when migrating from RefResolver to referencing #1312

def validate_schema(
    instance: dict[str, Any],
    schema: dict[str, Any],
    *,
    path: str,
    method: str,
    response: str,
    content: str = "application/json",
) -> None:
    try:
        _methods = schema["paths"][path]

    except KeyError:  # pragma: no cover (should never happen)
        msg = f"Path {path} not found in schema"
        raise ValueError(msg) from None

    try:
        _responses = _methods[method]

    except KeyError:  # pragma: no cover (should never happen)
        msg = f"Method {method} not found in schema"
        raise ValueError(msg) from None

    try:
        _content = _responses["responses"][response]["content"]

    except KeyError:  # pragma: no cover (should never happen)
        msg = f"Response {response} not found in schema"
        raise ValueError(msg) from None

    try:
        _schema = _content[content]["schema"]

    except KeyError:  # pragma: no cover (should never happen)
        msg = f"Content {content} not found in schema"
        raise ValueError(msg) from None

    openapi_schema_validator.validate(
        instance,
        _schema,
        cls=OAS30Validator,
        resolver=RefResolver.from_schema(schema),  # TODO: migrate to referencing lib
    )

resource = Resource.from_contents(schema, default_specification=DRAFT202012)
registry = Registry().with_resource("", resource)
openapi_schema_validator.validate(instance, _schema, registry=registry)