Implement JSON-RPC error codes

[adamschmideg]

As per EIPs/eip-1474.md at master · ethereum/EIPs. For details see this PR discussion

[hjlee9182]

Are you want to add -32005 error in docs?

[jacklightChen]

try to add -32006 error ^_^

[johnson73A]

Gjjgdjnk @jacklightChen

[howjmay]

Is this issue still needing help?

[MariusVanDerWijden]

We're currently trying to create a new standard for the JSON-RPC api which would also include better error codes, the progress of it can be found here: https://github.com/ethereum-oasis/eth1.x-JSON-RPC-API-standard/issues
Once we have a good api, we can start to implement this, until then this issue is on hold

[lhendre]

@MariusVanDerWijden Checked the link and nothing has been updated in awhile, is this still needed?

[MariusVanDerWijden]

This issue? not really, but more json-rpc error codes should be standardized (we've added more in the engine api)