prevent alternate streams from overwriting main stream for animations

src/dev-util/stereo-switch.gd

@@ -16,9 +16,11 @@ func update_mix_target():
 
 
 func play(from:float = 0.0) -> void:
+	if not alternate_streams == {}:
 		match State.speech_language:
 			1: stream = default_stream
 			2:
 				if alternate_streams.keys().has("de"):
 					stream = alternate_streams["de"]
+
 	super.play(from)