backend/account: fix bugs in account discovery

Recent commit 726289c made the account
Initialization asynchronous, moving the `account.ensureAddresses()` call
on a separate thread. This caused a regression inside
`backend.checkAccountUsed()` where the method wasn't waiting for the
complete account synchronization before marking it as used.

This commit fixes the issue waiting for account sync before checking if
it used.

This also fixes the `backend.Accounts()` method, that was returning the
original `backend.accounts` object instead of a copy. This caused the
caller to read the account list without a proper lock, causing weird
behaviors during account discovery.

Author: Beerosagos

backend/accounts.go

@@ -750,12 +750,16 @@ func (backend *Backend) addAccount(account accounts.Interface) {
 		})
 		if event.Subject == string(accountsTypes.EventSyncDone) {
 			backend.notifyNewTxs(account)
+			go backend.checkAccountUsed(account)
 		}
 	})
+	if err := account.Initialize(); err != nil {
+		backend.log.WithError(err).Error("error initializing account")
+		return
+	}
 	if backend.onAccountInit != nil {
 		backend.onAccountInit(account)
 	}
-	go backend.checkAccountUsed(account)
 }
 
 // The accountsAndKeystoreLock must be held when calling this function.
@@ -1529,10 +1533,6 @@ func (backend *Backend) checkAccountUsed(account accounts.Interface) {
 		}
 	}
 	log := backend.log.WithField("accountCode", account.Config().Config.Code)
-	if err := account.Initialize(); err != nil {
-		log.WithError(err).Error("error initializing account")
-		return
-	}
 	txs, err := account.Transactions()
 	if err != nil {
 		log.WithError(err).Error("discoverAccount")

backend/backend.go

@@ -22,6 +22,7 @@ import (
 	"net/url"
 	"os"
 	"path/filepath"
+	"slices"
 	"strings"
 	"time"
 
@@ -590,7 +591,7 @@ func (backend *Backend) Testing() bool {
 // Accounts returns the current accounts of the backend.
 func (backend *Backend) Accounts() AccountsList {
 	defer backend.accountsAndKeystoreLock.RLock()()
-	return backend.accounts
+	return slices.Clone(backend.accounts)
 }
 
 // KeystoreTotalAmount represents the total balance amount of the accounts belonging to a keystore.