Fix grammar error null error

and only reload current question upon encountering error

lib/pangea/analytics_practice/analytics_practice_page.dart

@@ -269,6 +269,25 @@ class AnalyticsPracticeState extends State<AnalyticsPractice>
     await _startSession();
   }
 
+  Future<void> reloadCurrentActivity() async {
+    if (activityTarget.value == null) return;
+
+    try {
+      activityState.value = const AsyncState.loading();
+      selectedMorphChoice.value = null;
+
+      final req = activityTarget.value!;
+      final res = await _fetchActivity(req);
+
+      if (!mounted) return;
+      activityState.value = AsyncState.loaded(res);
+      _playAudio();
+    } catch (e) {
+      if (!mounted) return;
+      activityState.value = AsyncState.error(e);
+    }
+  }
+
   Future<void> _completeSession() async {
     _sessionLoader.value!.finishSession();
     setState(() {});

lib/pangea/analytics_practice/analytics_practice_session_repo.dart

@@ -56,7 +56,7 @@ class AnalyticsPracticeSessionRepo {
             AnalyticsActivityTarget(
               target: PracticeTarget(
                 tokens: [entry.key],
-                activityType: types[targets.length],
+                activityType: ActivityTypeEnum.grammarCategory,
                 morphFeature: entry.value,
               ),
             ),
@@ -231,18 +231,23 @@ class AnalyticsPracticeSessionRepo {
         }
 
         final choices = igcMatch!.match.choices!.map((c) => c.value).toList();
-        final choiceTokens = tokens.where(
-          (token) =>
-              token.lemma.saveVocab &&
-              choices.any(
-                (choice) => choice.contains(token.text.content),
-              ),
-        );
+        final choiceTokens = tokens
+            .where(
+              (token) =>
+                  token.lemma.saveVocab &&
+                  choices.any(
+                    (choice) => choice.contains(token.text.content),
+                  ),
+            )
+            .toList();
+
+        // Skip if no valid tokens found for this grammar error
+        if (choiceTokens.isEmpty) continue;
 
         targets.add(
           AnalyticsActivityTarget(
             target: PracticeTarget(
-              tokens: choiceTokens.toList(),
+              tokens: choiceTokens,
               activityType: ActivityTypeEnum.grammarError,
               morphFeature: null,
             ),

lib/pangea/analytics_practice/analytics_practice_view.dart

@@ -329,7 +329,7 @@ class _ActivityChoicesWidget extends StatelessWidget {
                 ErrorIndicator(message: error.toString()),
                 const SizedBox(height: 16),
                 TextButton.icon(
-                  onPressed: controller.reloadSession,
+                  onPressed: controller.reloadCurrentActivity,
                   icon: const Icon(Icons.refresh),
                   label: Text(L10n.of(context).tryAgain),
                 ),