<!-- Thanks for contributing to the PokéAPI project. To make sure we're effective, please check the following: - Make sure your issue hasn't already been submitted on the issues tab. (It has search functionality!) - If your issue is one of outdated API data, please note that we get our data from [veekun](https://github.com/veekun/pokedex/). If they are not up to date either, please look for or create an issue there. Otherwise, feel free to create an issue here. - Provide a clear description of the issue. - Provide a clear description of the steps to reproduce. - Provide a clear description of the expected behavior. Thank you! --> Steps to Reproduce: 1. See [OpenAPI definition](https://github.com/PokeAPI/pokeapi/blob/46295d6f212c90d1024bc61e34c3ad7a35944fcf/openapi.yml#L8606-L8609) to ensure that `Region.main_generation` is not marked as nullable. 2. Access https://pokeapi.co/api/v2/region/hisui 3. `main_generation` is null.