diff --git a/lib/pangea/controllers/my_analytics_controller.dart b/lib/pangea/controllers/my_analytics_controller.dart
index deafd8f2a..4b7c8cc96 100644
--- a/lib/pangea/controllers/my_analytics_controller.dart
+++ b/lib/pangea/controllers/my_analytics_controller.dart
@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:developer';
 
 import 'package:fluffychat/pangea/controllers/pangea_controller.dart';
+import 'package:fluffychat/pangea/enum/construct_type_enum.dart';
 import 'package:fluffychat/pangea/models/student_analytics_summary_model.dart';
 import 'package:fluffychat/pangea/utils/error_handler.dart';
 import 'package:flutter/foundation.dart';
@@ -96,7 +97,7 @@ class MyAnalyticsController {
         saveFutures.add(
           analyticsRoom.saveConstructUsesSameLemma(
             uses.key,
-            uses.value.first.constructType!,
+            uses.value.first.constructType ?? ConstructType.grammar,
             uses.value,
             isEdit: isEdit,
           ),
diff --git a/lib/pangea/models/construct_analytics_event.dart b/lib/pangea/models/construct_analytics_event.dart
index a97950cdd..176d84bbd 100644
--- a/lib/pangea/models/construct_analytics_event.dart
+++ b/lib/pangea/models/construct_analytics_event.dart
@@ -36,6 +36,7 @@ class ConstructEvent {
     Client client,
   ) async {
     _contentCache ??= ConstructUses.fromJson(event.content);
+    if (_contentCache == null || _event.stateKey == null) return;
     final previousLength = _contentCache!.uses.length;
     _contentCache!.uses.removeWhere(
       (element) => removeIds.contains(element.msgId),