bug#31098: 27.0.50; emacsclient: create frame only if no frame exists

[Thomas Hisch]

I usually start emacsclient with the -n flag, which opens the specified 
file in an already created frame. However, if no emacs frame exists 
"emacsclient -n filename" silently exits and no frame is created. I know 
that there exists the -c option to create a new frame, but this creates 
a new frame for every emacsclient -nc invocation, which is not what I 
want (I only want to work with a single frame).

Do you think that it makes sense to automatically create a new frame
when "emacsclient -n" is called and no frame exists for the running
emacs daemon? (As I mentioned above, currently nothing happens) Or add a
new command line flag for this usecase?