Replace JSON-RPC error code literals with named constants

[csgui]

Currently, JSON-RPC error codes such as -32600, -32601, ... are represented as numeric literals throughout the codebase. These codes are defined by the JSON-RPC 2.0 specification.

Consider introduce named constants for all standard JSON-RPC error codes, for example:

JSON_RPC_INVALID_REQUEST = -32600
JSON_RPC_METHOD_NOT_FOUND = -32601
JSON_RPC_INVALID_PARAMS = -32602
JSON_RPC_INTERNAL_ERROR = -32603
.
.
.

Checkpoints:

• Replace all occurrences of numeric literals in the codebase with these named constants
• Reference the JSON-RPC specification in the constant definitions
• Tests for the implementation

[jaoleal]

Do you want to address that @csgui ? I could do this together with some small fixups for the server.

Should we locate jsonrpc specific related code, like these constants in floresta rpc ? Ive been thinking im importing more code from the jsonrpc crate that we depend to have more control over our types.

I also have a bug to address that ive found in the server that happens exactly because we are reimplementing the request and response types

[csgui]

Be my guest @jaoleal ! 🙏

IMO, the meanings of those codes should come from the crate that implements the full specification. Otherwise, we might incur the risk of drifting from upstream. If the jsonrpc crate is updated your wrappers could become outdated.

[luisschwab]

https://github.com/remix7531/bitcoin-rpc-errors