lnwallet/btcwallet: during initial creation catch the case of an existing wallet

In this commit, due to the recent changes within lnd itself, it may be
possible that a wallet already exists when the wallet has been signaled
to be created. As a result, *always* open the wallet ourselves, but
allow an existing wallet to already be in place.

lnwallet/btcwallet/btcwallet.go

@@ -80,21 +80,33 @@ func New(cfg Config) (*BtcWallet, error) {
 	var wallet *base.Wallet
 	if !walletExists {
 		// Wallet has never been created, perform initial set up.
-		wallet, err = loader.CreateNewWallet(pubPass, cfg.PrivatePass,
+		wallet, err = loader.CreateNewWallet(
-			cfg.HdSeed)
+			pubPass, cfg.PrivatePass, cfg.HdSeed,
-		if err != nil {
+		)
+
+		switch {
+		// If the wallet already exists, then we'll ignore this error
+		// and proceed directly to opening the wallet.
+		case err == base.ErrExists:
+
+		// Otherwise, there's a greater error here, and we'll return
+		// early.
+		case err != nil:
 			return nil, err
 		}
-	} else {
+
-		// Wallet has been created and been initialized at this point,
+		if err := loader.UnloadWallet(); err != nil {
-		// open it along with all the required DB namespaces, and the
-		// DB itself.
-		wallet, err = loader.OpenExistingWallet(pubPass, false)
-		if err != nil {
 			return nil, err
 		}
 	}
 
+	// Wallet has been created and been initialized at this point, open it
+	// along with all the required DB namepsaces, and the DB itself.
+	wallet, err = loader.OpenExistingWallet(pubPass, false)
+	if err != nil {
+		return nil, err
+	}
+
 	// Create a bucket within the wallet's database dedicated to storing
 	// our LN specific data.
 	db := wallet.Database()