query error behavior

[piscisaureus]

According to the readme, the client's 'error' event is emitted when a query has no callback / delegate for an error.

This works fine for queries that have been created with a callback. However if a delegate is attached through client.on('error', cb), the client's error event is emitted anyway.

Try:

query = client.query('this must be wrong');
query.on('error', function(err) {
  console.log('Failing gracefully: ' + error);
});

[piscisaureus]

Should be fairly easy to fix by checking if query.listeners('error').length > 1, and not throwing if that is the case.

[piscisaureus]

Patches and tests: http://github.com/piscisaureus/node-mysql/commits/query-error

[felixge]

Landed in db328a1 and e3bc7db. Improved test added in ffdc745.

Thanks for the patch!