Error handler syntax/signature error

[myselfhimself]

Hello,

this line raises errors when raised because response methods cannot be chained this way:
https://github.com/deepgram-devs/deepgram-node-proxy/blob/main/index.js#L34

It seems that error handler relies on different types of objects / APIs.

I will contribute a working one.

[myselfhimself]

Here is a related PR #4