Improve extensions errors design

[Asone]

Current field errors returned through extensions are quite limited in its design.

When a request should return data about payment, it should, aside the payment request field if a new invoice is generated, provide also an invoice state information, otherwise there is a potential bottleneck when handling query responses and conditional rendering on client side

[Asone]

Closing issue as bottleneck should be handled through the designed flow proposal at #8