import and merge 2

lib/screens/deck_import_screen.dart

@@ -144,9 +144,14 @@ class _DeckImportScreenState extends State<DeckImportScreen> {
       }
 
       final parsedDeck = _parseDeckFromJson(_jsonController.text.trim());
-      if (parsedDeck.questions.isEmpty) {
+      if (parsedDeck == null || parsedDeck.questions.isEmpty) {
-        throw FormatException('JSON deck must contain at least one question to merge');
+        throw FormatException(
+          parsedDeck == null
+              ? 'Failed to parse deck'
+              : 'JSON deck must contain at least one question to merge',
+        );
       }
+      final deckToMerge = parsedDeck;
 
       final deckStorage = DeckStorage();
       final existingDecks = deckStorage.getAllDecksSync();
@@ -189,7 +194,7 @@ class _DeckImportScreenState extends State<DeckImportScreen> {
       final timestamp = DateTime.now().millisecondsSinceEpoch;
       final mergedQuestions = [
         ...selectedDeck.questions,
-        ...parsedDeck.questions.asMap().entries.map((e) {
+        ...deckToMerge.questions.asMap().entries.map((e) {
           final q = e.value;
           final i = e.key;
           return q.copyWith(id: '${q.id}_merged_${timestamp}_$i');
@@ -200,7 +205,7 @@ class _DeckImportScreenState extends State<DeckImportScreen> {
 
       showTopSnackBar(
         context,
-        message: 'Added ${parsedDeck.questions.length} question(s) to "${selectedDeck.title}"',
+        message: 'Added ${deckToMerge.questions.length} question(s) to "${selectedDeck.title}"',
         backgroundColor: Colors.green,
       );
       Navigator.pop(context);