feat: add gRPC codes to errors

- new gRPC Codes have been added for better error matching retaining the old text for string matching
- first digit indicates server related error
- second digit indicates wallet related error
- the third and fourth digit error number for the combination

Signed-off-by: DarthBenro008 <[email protected]>

Author: DarthBenro008

rpcperms/interceptor.go

@@ -5,6 +5,8 @@ import (
 	"fmt"
 	"sync"
 
+	"google.golang.org/grpc/status"
+
 	"github.com/btcsuite/btclog"
 	grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware"
 	"github.com/lightningnetwork/lnd/lnrpc"
@@ -48,26 +50,26 @@ const (
 var (
 	// ErrWaitingToStart is returned if LND is still wating to start,
 	// possibly blocked until elected as the leader.
-	ErrWaitingToStart = fmt.Errorf("waiting to start, RPC services not " +
+	ErrWaitingToStart = status.Error(1001, "waiting to start, RPC services not "+
 		"available")
 
 	// ErrNoWallet is returned if the wallet does not exist.
-	ErrNoWallet = fmt.Errorf("wallet not created, create one to enable " +
+	ErrNoWallet = status.Error(0101, "wallet not created, create one to enable "+
 		"full RPC access")
 
 	// ErrWalletLocked is returned if the wallet is locked and any service
 	// other than the WalletUnlocker is called.
-	ErrWalletLocked = fmt.Errorf("wallet locked, unlock it to enable " +
+	ErrWalletLocked = status.Error(0102, "wallet locked, unlock it to enable "+
 		"full RPC access")
 
 	// ErrWalletUnlocked is returned if the WalletUnlocker service is
 	// called when the wallet already has been unlocked.
-	ErrWalletUnlocked = fmt.Errorf("wallet already unlocked, " +
+	ErrWalletUnlocked = status.Error(0103, "wallet already unlocked, "+
 		"WalletUnlocker service is no longer available")
 
 	// ErrRPCStarting is returned if the wallet has been unlocked but the
 	// RPC server is not yet ready to accept calls.
-	ErrRPCStarting = fmt.Errorf("the RPC server is in the process of " +
+	ErrRPCStarting = status.Error(1002, "the RPC server is in the process of "+
 		"starting up, but not yet ready to accept calls")
 
 	// macaroonWhitelist defines methods that we don't require macaroons to