protected InvokerResult errorResult(Query query, ErrorMessage errorMessage) {
        Result error = new Result(query, errorMessage);
        Coverage errorCoverage = new Coverage(0, 0, 0);
        errorCoverage.setNodesTried(1);
        error.setCoverage(errorCoverage);
        return new InvokerResult(error);
    }
@param query the query to send
@param context a context object that can be used to pass context among different
               invokers, e.g for reuse of preserialized data.
@return an object that can be passed to the next invocation of sendSearchRequest
container-search/src/main/java/com/yahoo/search/dispatch/SearchInvoker.java