Incorrect casting of getAs and family should throw an Exception, not a

warning.  Catch if you don't like it.

casbah-commons/src/main/scala/MongoDBObject.scala

@@ -116,7 +116,7 @@ class MongoDBObject(val underlying: DBObject = new BasicDBObject) extends Map[St
       case value if manifest[A] >:> Manifest.classType(value.getClass) =>
         Some(value.asInstanceOf[A])
       case fail => 
-        log.warn("Unable to cast '%s' as '%s'; please check your types.", Manifest.classType(fail.getClass), manifest[A])
+        throw new IllegalArgumentException("Unable to cast '%s' as '%s'; please check your types.".format(Manifest.classType(fail.getClass), manifest[A]))
         None
     }
   }