Evol return exception

[Ducarouge]

Hi and happy new year,

Thank you very much for this API witch is very useful.

We are using it in a big project for the IGN geoplatform and we need a cleaner way to catch the errors return by the API.

This PR offers a more consistent way to handle exceptions. I hope this does not impact to much the use of the API and i'm open to discussion.

It would be great if we can merge and continue to contribute to your project (and not in a fork).

[iamtekson]

Hi @Ducarouge, Happy New Year! and Thank you very much for your valuable contribution.

As I see, you have changed the multiple things in a same PR. It is little bit harder for me to review the full code. Let me get some time and review it soon. Thanks again for your time and contribution.