bug#67628: Emacs 29.1: (x-open-connection (getenv "DISPLAY")) gets "Display :0.0 does not exist" error

[Eli Zaretskii]

> Date: Mon, 4 Dec 2023 19:31:38 +0200
> From: Herman <mahlamytsike@gmail.com>
> 
> 'x-create-frame' succeeds, but 'x-open-connection' fails with same display 
> argument.
> 
> This error "Display :0.0 does not exist" happens only, when variable 
> 'debug-on-error' is non-nil. When 'debug-on-error' is nil, the error is not 
> present. I.e. it works on the principle - you get what you are looking for.

It could be that the code catches the error and proceeds, but your
setting debug-on-error non-nil prevents that.

Why do you need to set debug-on-error in that case?