bug#49675: 28.0.50; minibuffer-quit produces error

[Gregory Heytings]

> > > ‘minibuffer-quit’ produces this (or similar) error whenever I change 
> > > my mind and press ‘C-g’ before entering any text into the minibuffer 
> > > prompt. I have tried this at a couple of places. Simplest is this one. 
> > > Press ‘M-x’ and then press ‘C-g’ without entering any text on the 
> > > minibuffer prompt.
> >
> > I'm unable to reproduce this.
>
> So am I.

Note that the OP said: "this error does not occur with default 
configuration i.e. with ‘emacs -Q’. But this was not happening before the 
recent minibuffer changes. So I’ll try to isolate the cause."