Display matches on no input for vertico

[BooAA]

Below is what I used to reproduce the bug:

1. (setq mini-frame-standalone t) ;; this is a buggy option and I enable it intentionally
2. Call something with many candidates, for example: describe-function or describe-variable, then you may see something like this:
   

This is not 100% reproducible, you might have to try several times.

3. After 2 is success, now invoke find-file, then you'll get no candidate displayed when no input.
   

I use edebug to trace mini-frame--display and find problem occurs at this line. Actually, child frame displays normally at first but shrinks to height 1 immediately, so this may be a bug related to mini-frame-resize.

Reference: minad/vertico#34

[agenbite]

This happens too with selectrum. Single line shown with no input, populated as it should upon introducing a character.

[aaronjensen]

This is fixed in Emacs 29. It can be worked around on older Emacsen: minad/vertico#115 (comment)