rpcserver: Fix Error message returned by processRequest

[qustavo]

When processRequest can't find a rpc command, standardCmdResult returns a btcjson.ErrRPCMethodNotFound but it gets ignored and a btcjson.ErrRPCInvalidRequest is returned instead.

For example when I run the createwallet command

btcctl --simnet --rpcuser=foo --rpcpass=bar createwallet testWallet

This is the error message I get:

-32600: Invalid request: malformed

But instead I should get this (returned by standardCmdResult)

-32601: Method not found

This fixes processRequest behavior to return the right error message.

[coveralls]

Pull Request Test Coverage Report for Build 636199679

• 0 of 7 (0.0%) changed or added relevant lines in 1 file are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.009%) to 52.843%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rpcserver.go	0	7	0.0%

Files with Coverage Reduction	New Missed Lines	%
btcec/signature.go	3	92.76%
peer/peer.go	3	75.63%

Totals
Change from base Build 624441762:	-0.009%
Covered Lines:	20921
Relevant Lines:	39591

---

💛 - Coveralls

[jcvernaleo]

Good catch.
OK

[jcvernaleo]

@gchaincl looks good but any chance you could squash these to one commit (with just the one commit message)?

[jcvernaleo]

Change is good but if possible, squash would be nice to keep history clean.

Thanks!

[qustavo]

Sure, will do

[qustavo]

@jcvernaleo commits squashed

[jcvernaleo]

OK