davide@ubuntu:~/Desktop/agenda$ node tryAgenda.js

events.js:72
        throw er; // Unhandled 'error' event
              ^
MongoError: Invalid modifier specified $setOnInsert
    at toError (/home/davide/node_modules/agenda/node_modules/mongoskin/node_modules/mongodb/lib/mongodb/utils.js:110:11)
    at /home/davide/node_modules/agenda/node_modules/mongoskin/node_modules/mongodb/lib/mongodb/utils.js:157:34
    at /home/davide/node_modules/agenda/node_modules/mongoskin/node_modules/mongodb/lib/mongodb/db.js:1670:9
    at Server.Base._callHandler (/home/davide/node_modules/agenda/node_modules/mongoskin/node_modules/mongodb/lib/mongodb/connection/base.js:382:41)
    at /home/davide/node_modules/agenda/node_modules/mongoskin/node_modules/mongodb/lib/mongodb/connection/server.js:472:18
    at MongoReply.parseBody (/home/davide/node_modules/agenda/node_modules/mongoskin/node_modules/mongodb/lib/mongodb/responses/mongo_reply.js:68:5)
    at null.<anonymous> (/home/davide/node_modules/agenda/node_modules/mongoskin/node_modules/mongodb/lib/mongodb/connection/server.js:430:20)
    at EventEmitter.emit (events.js:95:17)
    at null.<anonymous> (/home/davide/node_modules/agenda/node_modules/mongoskin/node_modules/mongodb/lib/mongodb/connection/connection_pool.js:191:13)
    at EventEmitter.emit (events.js:98:17)