v2.2.0: added various safety checks to prevent rare crash errors

SPD-classes/src/main/java/com/watabou/noosa/Group.java

@@ -280,6 +280,7 @@ public class Group extends Gizmo {
 	}
 	
 	public synchronized void clear() {
+		if (length == 0) return;
 		for (int i=0; i < length; i++) {
 			Gizmo g = members.get( i );
 			if (g != null) {

SPD-classes/src/main/java/com/watabou/noosa/audio/Sample.java

@@ -79,9 +79,13 @@ public enum Sample {
 			@Override
 			public void run() {
 				for (String asset : toLoad) {
-					Sound newSound = Gdx.audio.newSound(Gdx.files.internal(asset));
-					synchronized (INSTANCE) {
-						ids.put(asset, newSound);
+					try {
+						Sound newSound = Gdx.audio.newSound(Gdx.files.internal(asset));
+						synchronized (INSTANCE) {
+							ids.put(asset, newSound);
+						}
+					} catch (Exception e){
+						Game.reportException(e);
 					}
 				}
 			}