bug#64405: `toggle-side-windows' with 3 or more side windows leads to error; reproducer included

[JD Smith]

From a fresh Emacs 28 emacs -Q:

(progn
  (display-buffer-in-side-window (get-buffer-create "AA") '((side . right) 
(slot . -1)))
  (display-buffer-in-side-window (get-buffer-create "BB") '((side . right) 
(slot . 0)))
  (display-buffer-in-side-window (get-buffer-create "CC") '((side . right) 
(slot . 1)))
  (window-toggle-side-windows)
  (window-toggle-side-windows))

Leads to the error `Specified root is not an ancestor of specified window’.  
This arises as:

Debugger entered--Lisp error: (error "Specified root is not an ancestor of 
specified win...")
  delete-other-windows-internal(nil #<window 16>)
  window-state-put((((min-height . 4) (min-width . 10) (min-height-ignore . 2) 
(min-width-ignore . 7) (min-height-safe . 1) (min-width-safe . 2) 
(min-pixel-height . 64) (min-pixel-width . 70) (min-pixel-height-ignore . 32) 
(min-pixel-width-ignore . 49) (min-pixel-height-safe . 16) 
(min-pixel-width-safe . 14)) leaf (pixel-width . 591) (pixel-height . 560) 
(total-width . 84) (total-height . 35) (normal-height . 1.0) (normal-width . 
1.0) (parameters (clone-of . #<window 3 on *scratch*>)) (buffer #<buffer 
*scratch*> (selected . t) (hscroll . 0) (fringes 8 8 nil nil) (margins nil) 
(scroll-bars nil 3 t nil 0 t nil) (vscroll . 0) (dedicated) (point . #<marker 
at 480 in *scratch*>) (start . #<marker at 1 in *scratch*>))) #<window 16>)
  window-toggle-side-windows()
  (progn (display-buffer-in-side-window (get-buffer-create "AA") '((side . 
right) (slot . -1))) (display-buffer-in-side-window (get-buffer-create "BB") 
'((side . right) (slot . 0))) (display-buffer-in-side-window (get-buffer-create 
"CC") '((side . right) (slot . 1))) (window-toggle-side-windows) 
(window-toggle-side-windows))
  (progn (progn (display-buffer-in-side-window (get-buffer-create "AA") '((side 
. right) (slot . -1))) (display-buffer-in-side-window (get-buffer-create "BB") 
'((side . right) (slot . 0))) (display-buffer-in-side-window (get-buffer-create 
"CC") '((side . right) (slot . 1))) (window-toggle-side-windows) 
(window-toggle-side-windows)))
  elisp--eval-last-sexp(nil)
  eval-last-sexp(nil)
  funcall-interactively(eval-last-sexp nil)
  command-execute(eval-last-sexp)

Strangely no error is seen with 1 or 2 side windows.