bug#43569: 28.0.50; Menu "Continue Tags Search" signals an error

[Eli Zaretskii]

> Date: Tue, 22 Sep 2020 13:44:36 -0700 (PDT)
> From: Drew Adams <drew.adams@oracle.com>
> 
> > >> I think "Continue Tags Search" should be disabled when it has no effect.
> > >
> > > I've done that now, in menu-bar+.el.  I use this, but
> > > perhaps someone can let me know if it's not the right,
> > > or best, condition to use.  (I use condition-case, not
> > > ignore-errors, for compatibility with older Emacs.)
> > >
> > > :enable (not (condition-case nil
> > >                  (tags-loop-eval tags-loop-scan)
> > >                (error t)))
> > 
> > I tried this, but it doesn't enable "Continue Tags Search"
> > after starting "Search Tagged Files...".  And I don't know
> > what else could be checked.
> 
> I think the xref changes broke the use of the tags code.
> You can use `M-x tags-loop-continue'.  I think that
> :enable code should work - and it does work for Emacs < 27.

I tried to fix this on the emacs-27 branch, please take a look.