Fix RPC error message regression

[DanGould]

I think we have a regression in error handling from the new reqwest RPC client to the bitcoincore-rpc crate calls, where the method would also be printed. It'd be nice to get the insight of which request exactly failed like we had in the past

Insufficient funds, for example, is now returning

"Error: RPC request failed with status: 500 Internal Server Error" which is not descriptive.

Originally posted by @DanGould in #945 (comment)

[bc1cindy]

Hey @DanGould!

I've fixed this in the #971 . The issue was that we were only looking at HTTP status codes instead of parsing the actual JSON-RPC error response from Bitcoin Core.

Now it properly extracts the method name and real error message:

• Before: "RPC request failed with status: 500 Internal Server Error"
• After: "RPC 'walletcreatefundedpsbt' failed: Insufficient funds"

Add comprehensive tests with real Bitcoin Core integration and all checks passing. Should be good to go!

[arminsabouri]

Now that we have the missing RPC methods in the async bitcoind rpc crate can we just upgrade to using that?

[DanGould]

I agree that such an update is now appropriate

[bc1cindy]

I've done a comprehensive analysis in #973 and believe this issue can be closed.