我一直在尝试为Node.JS API设置redis，并且遇到了以下错误：

util.js:634
  ctor.prototype = Object.create(superCtor.prototype, {
                          ^
TypeError: Object prototype may only be an Object or null: undefined
    at Function.create (native)
    at Object.exports.inherits (util.js:634:27)
    at Object.<anonymous> (/home/<user>/<project>/node_modules/redis/lib/parser/javascript.js:31:6)
    at Module._compile (module.js:460:26)
    at Object.Module._extensions..js (module.js:478:10)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Module.require (module.js:365:17)
    at require (module.js:384:17)
    at Object.<anonymous> (/home/<user>/<project>/node_modules/redis/index.js:33:14)

这是我的代码：

console.log('Redis: ' + config.redis.host);
console.log('Redis: ' + config.redis.port);
console.log('Redis: ' + config.redis.pass);

redis       = require('redis');
redisClient = redis.createClient(
    config.redis.port, 
    config.redis.host, 
    {
        auth_pass: config.redis.pass
    }
);

config只是带有config对象的require（’config’）文件。