Thanks. I'm not going to be very specific here because I'm too lazy to dig into that giant type, but if they want that method implementation to work without typ

Thanks. I'm not going to be very specific here because I'm too lazy to dig into that giant type, but if they want that method implementation to work without type assertions then the `add` method would need to be typed as an assertion function[1] so the type system can understand that it narrows its argument[2]. Here's an example: https://tsplay.dev/w8y9PN https://tsplay.dev/w8y9PN [1]: https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#assertion-functions https://www.typescriptlang.org/docs/handbook/release-notes/t... [2]: Doing this isn't safe anyway because it mutates an object in a type-relevant way while there may other variables referring to it (the safe thing to do is return a new `Elysia` instance from `get`), but that's beside the point.