bug#43973: 28.0.50; [NS] Two crashes on macOS

[Andrii Kolomoiets <andreyk.mad@gmail.com>]

Alan Third <alan@idiocy.org> writes:

> On Tue, Oct 13, 2020 at 10:35:28AM +0300, Andrii Kolomoiets wrote:
>> 1. M-x tool-bar-mode
>> 2. Evaluate
>>     (let ((params `((parent-frame . ,(selected-frame))
>>                     (undecorated . t))))
>>       (dotimes (_z 100)
>>         (set-face-background 'internal-border "black"
>>                              (make-frame params))))
>> 3. Move the frame
>
> I can replicate this one, every time.
>
> +      if (!face)
> +        return;
>
> "fixes" it, but leaves Emacs in a bit of a strange state where I can
> only see one frame and it's incredibly slow.

It's because all child frames are undecorated.  Just remove
'(undecorated . t)' from 'params' and you'll see all the frames.