Fix crash caused by invalid mix_rate assignment due to bogus

project settings.

We'll default to a sensible value in the case that a user has
somehow managed to modify the configuration file incorrectly.

Closes 69819

drivers/pulseaudio/audio_driver_pulseaudio.cpp

@@ -293,7 +293,7 @@ Error AudioDriverPulseAudio::init() {
 	active.clear();
 	exit_thread.clear();
 
-	mix_rate = GLOBAL_GET("audio/driver/mix_rate");
+	mix_rate = _get_configured_mix_rate();
 
 	pa_ml = pa_mainloop_new();
 	ERR_FAIL_COND_V(pa_ml == nullptr, ERR_CANT_OPEN);