TypeScript: Incorrect subject type from returning a wrapped `undefined` from `.then`

[NicholasBoll]

It is valid to return a wrapped undefined. Example: cy.wrap(undefined) or Promise.resolve(undefined) or even cy.wrap(null).

In this case, the subject is a wrapped undefined instead of an unwrapped undefined.

• Operating System: N/A
• Cypress Version: 1.4.1
• Browser Version: N/A

Is this a Feature or Bug?

Bug

Current behavior:

cy.get('body')
  .then(() => cy.wrap(undefined))
  .then((subject) => {
    subject // Cypress.Chainable<undefined>
  })

Desired behavior:

cy.get('body')
  .then(() => cy.wrap(undefined))
  .then((subject) => {
    subject // undefined
  })

How to reproduce:

See "Current behavior"

Test code:

See "Current behavior"

Additional Info (images, stack traces, etc)

PR is on the way

[brian-mann]

Released in 1.4.2.