M_SoundTestNextPrev: Set cv_soundtest to 0 when returning to the soundtest entry

src/menus/transient/sound-test.c

@@ -63,6 +63,7 @@ static void M_SoundTestMainControl(INT32 choice)
 	{
 		soundtest.current = NULL;
 		soundtest.currenttrack = 0;
+		CV_SetValue(&cv_soundtest, 0);
 	}
 }
 

src/s_sound.c

@@ -1582,6 +1582,11 @@ updatecurrent:
 			? newdef->numtracks-1
 			: 0;
 
+	if (newdef == NULL)
+	{
+		CV_SetValue(&cv_soundtest, 0);
+	}
+
 updatetrackonly:
 	if (soundtest.playing == true)
 	{