Hello,

I am attempting to connect to mongodb using the following code

import * as mongodb from 'mongodb';
console.log('Attempting connection...');
const dbPromise = mongodb.MongoClient.connect(mongodbUrl);
dbPromise.then(() => {
  console.log('connected!');
});

I am on node v6.10, and started with the following libraries:

mongodb-core 2.1.17
mongodb 2.2.33

When running the above code, I would intermittently get the following error:

(node:76520) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): MongoError: no connection available

In the process of trying to address this issue, I upgraded my driver:

mongodb-core 2.1.19
mongodb 2.2.35

Now, the connection promise neither fails nor resolves. I ran this with `loggingLevel: 'debug'`, and got the output in mongolog.txt (attached).