Recipe:

- start up conkeror
- do C-x C-f bla://asd.fg
  an alert box is shown telling us that bla is not a registered protocol 
- after clicking OK an exception is shown in the mini-buffer
- do M-n and from now on the tab-bar is no longer refreshed when switching buffers with M-n and M-p
  until tab-bar mode is disabled and re-enabled (twice M-x tab-bar-mode )
  instead each buffer change triggers an error
- last step reveals the tab for the buffer for bla://asd.fg.