slightly improved error message (take 2)
slightly improved error message (take 2)

apache/incubator-groovy,apache/groovy,paulk-asert/groovy,paulk-asert/groovy,paulk-asert/groovy,apache/groovy,apache/incubator-groovy,apache/incubator-groovy,apache/incubator-groovy,apache/groovy,paulk-asert/groovy,apache/groovy