I need a button to create a draft and update the current card, however I can only get 1 of those to work at a time.

// onGmailMessage.gs
CardService.newTextButton()
    .setText('Create draft and update card')
    .setComposeAction(CardService.newAction().setFunctionName('updateDraft'), CardService.ComposedEmailType.REPLY_AS_DRAFT)

This works:

  // updateDraft()
  return CardService.newComposeActionResponseBuilder()
    .setGmailDraft(draft)
    .build()

This doesn’t work:

  // FIXME: The value returned from Apps Script has a type that cannot be used by the add-ons platform. Also make sure to call build on any builder before returning it.
  return [
    // Update the draft
    CardService.newComposeActionResponseBuilder().setGmailDraft(draft).build(),
    // Update the card
    CardService.newActionResponseBuilder()
      .setNavigation(
        CardService.newNavigation().popToRoot().updateCard(onGmailMessage(e))
      )
      .setStateChanged(true)
      .build(),
  ]