v0.3.0b: fixed a crash bug with the sniper's mark

src/com/shatteredpixel/shatteredpixeldungeon/actors/buffs/SnipersMark.java

@@ -53,7 +53,8 @@ public class SnipersMark extends FlavourBuff {
 
 	@Override
 	public String desc() {
-		return "The sniper is honed in on the nearby " + ((Char)Actor.findById(object)).name + ", " +
+		Char ch = (Char)Actor.findById(object);
+		return "The sniper is honed in " + ((ch == null) ? "on a lost target" : "on the nearby" + ch.name ) + ", " +
 				"gaining increased attack speed and armor penetration while attacking it.\n" +
 				"\n" +
 				"The sniper will remain honed in until she switches targets, stops attacking, or the target dies.";