v3.1.0: added a few crash safety checks

core/src/main/java/com/shatteredpixel/shatteredpixeldungeon/actors/Char.java

@@ -586,7 +586,9 @@ public abstract class Char extends Actor {
 			
 		} else {
 
-			enemy.sprite.showStatus( CharSprite.NEUTRAL, enemy.defenseVerb() );
+			if (enemy.sprite != null){
+				enemy.sprite.showStatus( CharSprite.NEUTRAL, enemy.defenseVerb() );
+			}
 			if (visibleFight) {
 				//TODO enemy.defenseSound? currently miss plays for monks/crab even when they parry
 				Sample.INSTANCE.play(Assets.Sounds.MISS);

core/src/main/java/com/shatteredpixel/shatteredpixeldungeon/actors/buffs/EnhancedRings.java

@@ -37,7 +37,7 @@ public class EnhancedRings extends FlavourBuff {
 	@Override
 	public boolean attachTo(Char target) {
 		if (super.attachTo(target)){
-			if (target instanceof Hero) ((Hero) target).updateHT(false);
+			if (target == Dungeon.hero) ((Hero) target).updateHT(false);
 			return true;
 		}
 		return false;
@@ -46,7 +46,7 @@ public class EnhancedRings extends FlavourBuff {
 	@Override
 	public void detach() {
 		super.detach();
-		if (target instanceof Hero) ((Hero) target).updateHT(false);
+		if (target == Dungeon.hero) ((Hero) target).updateHT(false);
 	}
 
 	@Override

core/src/main/java/com/shatteredpixel/shatteredpixeldungeon/sprites/MobSprite.java

@@ -67,7 +67,7 @@ public class MobSprite extends CharSprite {
 			health.killAndErase();
 		}
 		
-		parent.add( new ScaleTweener( this, new PointF( 0, 0 ), FALL_TIME ) {
+		if (parent != null) parent.add( new ScaleTweener( this, new PointF( 0, 0 ), FALL_TIME ) {
 			@Override
 			protected void onComplete() {
 				MobSprite.this.killAndErase();