fix: prevent NoMethodError in foreign_account? when account family is nil (#1376)

Co-authored-by: sentry[bot] <39604003+sentry[bot]@users.noreply.github.com>

app/models/account/market_data_importer.rb

@@ -90,6 +90,7 @@ class Account::MarketDataImporter
     end
 
     def foreign_account?
+      return false if account.family.nil?
       account.currency != account.family.currency
     end
 end