Change the way we determine whether current user is signed in or not

lib/helpers/account_helper.dart

@@ -194,6 +194,9 @@ class AccountHelper {
     _currentUserID = preferences.getInt(_USER_ID_PREFERENCE_NAME);
   }
 
+  /// Check if current user ID is loaded or not
+  static bool get isUserIDLoaded => _currentUserID > 0;
+
   /// Get the ID of the currently signed in user
   static int getCurrentUserID() {
     if (_currentUserID == -1) throw "Current user ID has not been loaded yet!";