Fix unnecessary logging when calling sendFile

[xrnss]

The code basically says: if (error) return log(error) else log(error) which results in

This change should fix this confusing and unnecessary error logging

[endel]

Thank you @xrnss 🎉

[xrnss]

Is there anything else I can do to contribute to this library? This project was a complete life saver for me when I had to run an express nodejs server and websocket server over a single port! Thanks for everything you've done :)