NPE when trying to scan wildcard --source

[drewr]

Because you can't get a _mapping for a wildcard, stream2es es hits this when --target doesn't exist. Would be better to print a helpful error like, Wildcard --source detected, you have to create --target manually.

% stream2es es --source http://localhost:9200/foo\* --target http://localhost:9200/foo3 --log debug
2014-10-14T10:06:57.274-0500 DEBUG create index http://localhost:9200/foo3
java.lang.NullPointerException
        at clojure.core$val.invoke(core.clj:1489)
        at stream2es.es$idx_meta.invoke(es.clj:112)
        at stream2es.es$mapping.invoke(es.clj:116)
        at stream2es.stream.es$fn__2981.invoke(es.clj:47)
        at stream2es.stream$fn__2794$G__2774__2801.invoke(stream.clj:16)
        at stream2es.main$ensure_index.invoke(main.clj:306)
        at stream2es.main$main.invoke(main.clj:318)
        at stream2es.main$_main.doInvoke(main.clj:336)
        at clojure.lang.RestFn.invoke(RestFn.java:551)