public static void throwModelNotReady() {
        throw new NotFoundException("Config not available, verify that an application package has been deployed and activated.");
    }
Throws an exception if bad config or config id

@param requestKey     a {@link com.yahoo.vespa.config.ConfigKey}
@param requestHandler a {@link RequestHandler}
@param appId appId
configserver/src/main/java/com/yahoo/vespa/config/server/http/HttpConfigRequest.java