Juri Linkov <juri@linkov.net> writes:

>> 1. (setq debug-on-error t enable-recursive-minibuffers t)
>> 2. M-:   (or any other prompt like 'M-x')
>> 3. Resize the minibuffer window e.g. with the mouse to at least 4 lines high
>> 4. M-x windmove-swap-states-up RET
>> 5. Click on the bottom window
>> 6. C-x t 2
>> 7. Click on the bottom window
>> 8. C-x t 2
>>
>> Debugger entered--Lisp error: (error "Specified root is not an ancestor of specified win...")
>>   delete-other-windows-internal(#<window 4 on *scratch*> #<window 7 on  *Minibuf-1*>)
>>   delete-other-windows()
>>   tab-bar-new-tab-to()
>>   tab-new(nil)
>
> Maybe the simplest fix is just not to create such a broken
> window configuration:
>
> diff --git a/lisp/windmove.el b/lisp/windmove.el
> index 06ce16c0d42..57511291588 100644
> --- a/lisp/windmove.el
> +++ b/lisp/windmove.el
> @@ -724,6 +724,8 @@ windmove-swap-states-in-direction
>                                             nil windmove-wrap-around 'nomini)))
>      (cond ((or (null other-window) (window-minibuffer-p other-window))
>             (user-error "No window %s from selected window" dir))
> +          ((window-minibuffer-p (selected-window))
> +           (user-error "Selected window is the minibuffer"))
>            (t
>             (window-swap-states nil other-window)))))