bug#63555: emacs 29 complains that it can't connect to the display

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

> What function(s) is/are used at that point which tells us a GUI
> session is impossible?

window-system-initialization.

> Can we invoke those same functions earlier during startup to realize
> this fact where we still can start as -nw?

Unfortunately not.  At least, not enough to make a change suitable for
the release branch.