@Override
    public Result search(Query query, Execution execution) {
        ErrorMessage e = validate(query);
        return (e != null)
                ? new Result(query, e)
                : execution.search(query);
    }
Validates that the attribute given as match-phase override is actually a valid numeric attribute
with fast-search enabled.

@author baldersheim
container-search/src/main/java/com/yahoo/search/searchers/ValidateMatchPhaseSearcher.java