Nokia: Sound: Add null pointer checks on get/setGain.

Some games seem to try using those with players they have just
closed, like Saboteur.

src/com/nokia/mid/sound/Sound.java

@@ -178,12 +178,13 @@ public void resume()
 	public void setGain(int gain) 
 	{ 
 		// Gain goes from 0 to 255, while setLevel works from 0 to 100
-		((PlatformPlayer.volumeControl)player.getControl("VolumeControl")).setLevel((int) (gain / 255 * 100));
+		if(player != null) { ((PlatformPlayer.volumeControl)player.getControl("VolumeControl")).setLevel((int) (gain / 255 * 100)); }
 	}
 
 	public int getGain() 
 	{ 
-		return (int) ((((PlatformPlayer.volumeControl)player.getControl("VolumeControl")).getLevel() / 100) * 255);
+		if(player != null) { return (int) ((((PlatformPlayer.volumeControl)player.getControl("VolumeControl")).getLevel() / 100) * 255); }
+		return 0;
 	}
 
 	public void setSoundListener(SoundListener soundListener) { ((PlatformPlayer) player).setSoundListener(this, soundListener); }