audio/pw: Report more accurate error when connecting to PipeWire fails

According to its man page [1], pw_context_connect() sets errno on
failure:

  Returns a Core on success or NULL with errno set on error.

It may be handy to see errno when figuring out why PipeWire
failed to connect. That leaves us with just one possible path to
reach 'fail_error' label which is then moved to that path and
also its error message is adjusted slightly.

1: https://docs.pipewire.org/group__pw__core.html#ga5994e3a54e4ec718094ca02a1234815b

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-ID: <3a78811ad5b0e87816b7616ab21d2eeef00b9c52.1726647033.git.mprivozn@redhat.com>

audio/pwaudio.c

@@ -769,13 +769,15 @@ qpw_audio_init(Audiodev *dev, Error **errp)
     pw->core = pw_context_connect(pw->context, NULL, 0);
     if (pw->core == NULL) {
         pw_thread_loop_unlock(pw->thread_loop);
-        goto fail_error;
+        error_setg_errno(errp, errno, "Failed to connect to PipeWire instance");
+        goto fail;
     }
 
     if (pw_core_add_listener(pw->core, &pw->core_listener,
                              &core_events, pw) < 0) {
         pw_thread_loop_unlock(pw->thread_loop);
-        goto fail_error;
+        error_setg(errp, "Failed to add PipeWire listener");
+        goto fail;
     }
     if (wait_resync(pw) < 0) {
         pw_thread_loop_unlock(pw->thread_loop);
@@ -785,8 +787,6 @@ qpw_audio_init(Audiodev *dev, Error **errp)
 
     return g_steal_pointer(&pw);
 
-fail_error:
-    error_setg(errp, "Failed to initialize PW context");
 fail:
     if (pw->thread_loop) {
         pw_thread_loop_stop(pw->thread_loop);