error

/Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-connector-mongodb/node_modules/mongodb/lib/utils.js:98
    process.nextTick(function() { throw err; });
                                  ^

TypeError: cb is not a function
    at /Users/Coding/Development/Vegies/VegiesServer/server/boot/challenge.js:33:11
    at /Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-datasource-juggler/lib/dao.js:1479:9
    at Object.async.each (/Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-datasource-juggler/node_modules/async/lib/async.js:153:20)
    at allCb (/Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-datasource-juggler/lib/dao.js:1417:13)
    at /Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-connector-mongodb/lib/mongodb.js:729:9
    at handleCallback (/Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-connector-mongodb/node_modules/mongodb/lib/utils.js:96:12)
    at /Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-connector-mongodb/node_modules/mongodb/lib/cursor.js:842:16
    at handleCallback (/Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-connector-mongodb/node_modules/mongodb/node_modules/mongodb-core/lib/cursor.js:249:5)
    at setCursorNotified (/Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-connector-mongodb/node_modules/mongodb/node_modules/mongodb-core/lib/cursor.js:569:3)
    at /Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-connector-mongodb/node_modules/mongodb/node_modules/mongodb-core/lib/cursor.js:677:16
    at queryCallback (/Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-connector-mongodb/node_modules/mongodb/node_modules/mongodb-core/lib/cursor.js:328:5)
    at Callbacks.emit (/Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-connector-mongodb/node_modules/mongodb/node_modules/mongodb-core/lib/topologies/server.js:95:3)
    at null.messageHandler (/Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-connector-mongodb/node_modules/mongodb/node_modules/mongodb-core/lib/topologies/server.js:243:23)
    at Socket.<anonymous> (/Users/Coding/Development/Vegies/VegiesServer/node_modules/loopback-connector-mongodb/node_modules/mongodb/node_modules/mongodb-core/lib/connection/connection.js:262:22)
    at emitOne (events.js:77:13)
    at Socket.emit (events.js:169:7)