fix(@clack/core,@clack/prompts): add non empty opts type interface

[kevduc]

This PR addresses this issue https://github.com/natemoo-re/clack/issues/144.

The current implementation is erroring out at runtime, the implementation in this PR shows a type error in the IDE/tsc instead.

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[kevduc]

Example of what the type error could look like in VSCode:

[cpreston321]

Hey @kevduc ! Thanks for this PR! 🙏🏼

I recently merged a PR to simplify types on @clack/prompts if you want to resolve issues -- I can then be able to merge this!

I could also see this being used also on https://github.com/natemoo-re/clack/blob/7c7fde8dcdfa1edc3feb131331290affbaa6d934/packages/prompts/src/index.ts#L307 & https://github.com/natemoo-re/clack/blob/7c7fde8dcdfa1edc3feb131331290affbaa6d934/packages/prompts/src/index.ts#L423

[kevduc]

@cpreston321 Thanks for the suggestions!
The fix for MultiSelectOptions is pretty much the same as for select (https://github.com/natemoo-re/clack/pull/145/commits/20cde30e5e48fbe2b15a8d5dba2ae8f9845a4489). I also had a look at GroupMultiSelectPrompt:

• it looks like it doesn't make sense to have an empty list of options for a given group (and it currenlty is buggy, see https://stackblitz.com/edit/node-51onk7?file=index.ts, the test3 group looks selected, it can't be toggled, and when pressing enter it says nothing is selected), so the typing is fixed in https://github.com/natemoo-re/clack/pull/145/commits/f663d0f7e2a37ba7a088ac08f92c9e13a72dffe7:
• it also looks like there's another bug when options itself is empty (see https://stackblitz.com/edit/node-dhmjec?file=index.ts, press space to make it crash):

  TypeError: Cannot read properties of undefined (reading 'group')
      at CD.toggleValue (file:///home/projects/node-dhmjec/node_modules/@clack/core/dist/index.mjs:40:1272)
      at Object.eval [as cb] (file:///home/projects/node-dhmjec/node_modules/@clack/core/dist/index.mjs:40:1049)
      at CD.emit (file:///home/projects/node-dhmjec/node_modules/@clack/core/dist/index.mjs:35:1851)
      at CD.onKeypress (file:///home/projects/node-dhmjec/node_modules/@clack/core/dist/index.mjs:35:2130)
  

  I tried an approach where I use a NonEmptyObject type on options in GroupMultiSelectOptions, i.e. something like this:

  // packages\core\src\utility-types.ts
  export type NonEmptyObject<T> = keyof T extends never ? never : T;
  
  // packages\core\src\prompts\group-multiselect.ts
  interface GroupMultiSelectOptions<
      T extends { value: any },
      U extends Record<string, NonEmptyArray<T>> = Record<string, NonEmptyArray<T>>
  > extends PromptOptions<GroupMultiSelectPrompt<T, U>> {
      options: NonEmptyObject<U>;
      initialValues?: T['value'][];
      required?: boolean;
      cursorAt?: T['value'];
  }
  

  but that pretty much breaks the inference of Value for groupMultiselect (it ends up always being unknown) and I didn't manage to make it work (might need to refactor to have the type of value as a generic instead of the type of option { value: any }), so I've not added it to this MR, and if there's no straightforward fix, that's something that can be looked at in a different MR. An idea would be to at least do a runtime check and throw a more meaningful error.