socket.bind() with bogus or unavailable address fails silently

Calling socket.bind with a bogus or unavailable address causes the process to fail silently. Example:

'use strict';

const dnsSocket = require('.')
const socket = dnsSocket({retries: 0, timeout: 5000});

new Promise(function (fulfill, reject){
    socket.on('error', reject);

    try{
        socket.bind(null, '8.8.8.8', fulfill);
    }
    catch(e){
        return reject(e);
    }
})
.then(function(){
    console.log('socket bound');
    socket.destroy();
})
.catch(function(err){
    console.log('caught error', err);
});

When I run this with Node 6, there is no output, no errors caught, and the script exits prematurely. Looks like dns-socket emits a 'warning' instead of an 'error' in this case.

PR incoming.

Edit: just my $.02: I think this function in index.js should not try to pick/choose which errors constitute emitting a warning vs. an error, but should always emit an error instead:

  function onerror (err) {
    if (err.code === 'EACCES' || err.code === 'EADDRINUSE') {
      self.emit('error', err)
    } else {
      self.emit('warning', err)
    }
  }

Start in index.js at the onerror function shown in the issue and reproduce the problem with the provided Node.js example. Done means binding to a bogus or unavailable address produces observable error output and reaches the example's catch handler instead of exiting silently.