Asynchronous error handling in quick pick

[TylerLeonhardt]

Follow up from #173716

Here are three common scenarios in notebooks where we want to present warning/error messages to users and improve the UX
...

• Empty results from a quick pick item entry. This usually happens when users pick a quick pick item, which goes to the next quick pick step, but at the end there is no result in that step. We currently show a placeholder quick pick item there but

  • It might be too late to show this option
  • The quick pick item is not actionable and also doesn't look like a warning/error message, compared to the validation message we usually show in quick picks.

Two options (both of which assume that you don't go to a new empty quick pick):

• In quickpick, we have a core feature called validationMessage which shows a barebones message underneath the input. It is not like the input message validation which looks like it is attached to the input, it's just a piece of text right under the input. We could use this to display an error to the user that "something went wrong with that choice"
• just show an error notification

[TylerLeonhardt]

@rebornix @DonJayamanne can you attach a screenshot of the current experience?

cc @daviddossett for thoughts

[TylerLeonhardt]

Closing this since it's not talked about anymore