`Cypress.Commands.add` type doesn't take into account `prevSubject` to define the type of the custom command

Current behavior

declare global {
  namespace Cypress {
    interface Chainable {
      /**
       * Custom command to select DOM element by data-cy attribute.
       * @example cy.dataCy('greeting')
       */
      dataCy<E extends Node = HTMLElement>(value: string): Chainable<JQuery<E>>;
    }
  }
}

Cypress.Commands.add(
    'dataCy',
    { prevSubject: 'optional' },
    (subject, value) => {
      return cy.get(`[data-cy=${value}]`, {
        withinSubject: subject,
      });
    },
  );

subject and value are inferred as any as prevSubject isn’t taken into account and TS expect a single param If value is removed, the first param becomes string which is wrong The same problem applies to child commands

Desired behavior

Types should take into consideration prevSubject and use it into a conditional to provide correct typings There may be other edge cases with element | document | window

Test code to reproduce

https://github.com/cypress-io/cypress/pull/17496/files#diff-facdf706a5238380b5e97c040bc1a5f5cb89e3116f878754dd7fb4e693787715R77

This test is wrong, it should be

Cypress.Commands.add('newCommand', { prevSubject: true }, (subject, arg) => {
    // $ExpectType string
    arg
    return
  })

Cypress Version

9.0.0

Other

No response

[villanuevaSEAT]

We have the same issue 😢

[Nodonisko]

Also this test for optional subject should be added:

Cypress.Commands.add('newCommand', { prevSubject: 'optional' }, (subject, arg) => {
    // $ExpectType string
    arg
    return
  })