Check for bittrex error codes

[saschb2b]

I currently don't check for a returned error code from bittrex, just assume it works. Bittrex return an error object when a problem occured

{
  code: string
}

The error codes can be found here https://bittrex.github.io/api/v3#topic-Error-Codes

Extending the api return types with this object and handling the error cases would be the goal