t4515.scala:37: error: type mismatch;
 found   : _0(in value $anonfun) where type _0(in value $anonfun)
 required: (some other)_0(in value $anonfun) where type +(some other)_0(in value $anonfun)
        handler.onEvent(target, ctx.getEvent, node, ctx)
                                    ^
one error found