Playground

I have a function signature like this: const func = <TParams extends Record<string, any> = never> (...args: TParams extends never ? never[] : [TParams]) => {}

In my mind, this means that if no type is provided, func can be called without args, and if there is a type, func must be called with an arg of the corresponding type.

However, the type checker always assigns never (not never[]) to args if no type is given. This wasn't an issue before TS 5.0, but since the switch, I've been getting this error:

Argument of type '[]' is not assignable to parameter of type 'never'.

If the conditional parses correctly, it should have returned args as never[], but it doesn't. Am I understanding the never type wrong?