refactor: Return BResult from restoreWallet

Author: MacroFake

src/interfaces/wallet.h

@@ -329,7 +329,7 @@ class WalletLoader : public ChainClient
    virtual std::string getWalletDir() = 0;
 
    //! Restore backup wallet
-   virtual std::unique_ptr<Wallet> restoreWallet(const fs::path& backup_file, const std::string& wallet_name, bilingual_str& error, std::vector<bilingual_str>& warnings) = 0;
+   virtual BResult<std::unique_ptr<Wallet>> restoreWallet(const fs::path& backup_file, const std::string& wallet_name, std::vector<bilingual_str>& warnings) = 0;
 
    //! Return available wallets in wallet directory.
    virtual std::vector<std::string> listWalletDir() = 0;

src/qt/walletcontroller.cpp

@@ -391,9 +391,10 @@ void RestoreWalletActivity::restore(const fs::path& backup_file, const std::stri
         tr("Restoring Wallet <b>%1</b>…").arg(name.toHtmlEscaped()));
 
     QTimer::singleShot(0, worker(), [this, backup_file, wallet_name] {
-        std::unique_ptr<interfaces::Wallet> wallet = node().walletLoader().restoreWallet(backup_file, wallet_name, m_error_message, m_warning_message);
+        auto wallet{node().walletLoader().restoreWallet(backup_file, wallet_name, m_warning_message)};
 
-        if (wallet) m_wallet_model = m_wallet_controller->getOrCreateWallet(std::move(wallet));
+        m_error_message = wallet ? bilingual_str{} : wallet.GetError();
+        if (wallet) m_wallet_model = m_wallet_controller->getOrCreateWallet(wallet.ReleaseObj());
 
         QTimer::singleShot(0, this, &RestoreWalletActivity::finish);
     });

src/wallet/interfaces.cpp

@@ -569,11 +569,13 @@ class WalletLoaderImpl : public WalletLoader
         options.require_existing = true;
         return MakeWallet(m_context, LoadWallet(m_context, name, true /* load_on_start */, options, status, error, warnings));
     }
-    std::unique_ptr<Wallet> restoreWallet(const fs::path& backup_file, const std::string& wallet_name, bilingual_str& error, std::vector<bilingual_str>& warnings) override
+    BResult<std::unique_ptr<Wallet>> restoreWallet(const fs::path& backup_file, const std::string& wallet_name, std::vector<bilingual_str>& warnings) override
     {
         DatabaseStatus status;
-
-        return MakeWallet(m_context, RestoreWallet(m_context, backup_file, wallet_name, /*load_on_start=*/true, status, error, warnings));
+        bilingual_str error;
+        BResult<std::unique_ptr<Wallet>> wallet{MakeWallet(m_context, RestoreWallet(m_context, backup_file, wallet_name, /*load_on_start=*/true, status, error, warnings))};
+        if (!wallet) return error;
+        return wallet;
     }
     std::string getWalletDir() override
     {