No 404 handling route

[LuisFloresV]

Just to report there's no middleware to handle the 404.

[KostaSav]

Hi @LuisFloresV ,

I have added a commit, based on How add middleware for 404 errors on express.

Can you please elaborate on why we need this?

Also, feel free to create a pull request with any further changes you consider necessary. Perhaps we can create a nice 404 error page with a Harry Potter image.

Thanks!