Fix process X is not a subprocess errors

When killing repl popups with special processes (e.g. for cider).

modules/ui/popup/autoload/popup.el

@@ -21,7 +21,8 @@ the buffer is visible, then set another timer and try again later."
                (let ((kill-buffer-hook (remq '+popup-kill-buffer-hook-h kill-buffer-hook))
                      confirm-kill-processes)
                  (when-let (process (get-buffer-process buffer))
-                   (kill-process process))
+                   (when (eq (process-type process) 'real)
+                     (kill-process process)))
                  (let (kill-buffer-query-functions)
                    ;; HACK The debugger backtrace buffer, when killed, called
                    ;;      `top-level'. This causes jumpiness when the popup