bug#38384: (next|previous)-buffer silent about not switching

[martin rudalics]

> In some circumstances, next-buffer and previous-buffer do not have any
> buffer to switch to, and in that case they silently do nothing.  (Strictly
> speaking, they call switch-to-(next|prev)-buffer, which do nothing and
> return nil).
>
> I think they should throw a user-error, to inform the user about the
> situation.

Right.  Please install your patch.

martin