Safely access browser navigator.deviceMemory (#3268)

Author: denrase

CHANGELOG.md

@@ -11,6 +11,10 @@
 
 - Prefix firebase remote config feature flags with `firebase:` ([#3258](https://github.com/getsentry/sentry-dart/pull/3258))
 
+### Fixes
+
+- Safely access browser `navigator.deviceMemory` ([#3268](https://github.com/getsentry/sentry-dart/pull/3268))
+
 ## 9.7.0-beta.5
 
 ### Dependencies

packages/dart/lib/src/event_processor/enricher/web_enricher_event_processor.dart

@@ -1,4 +1,5 @@
 import 'package:web/web.dart' as web show window, Window, Navigator;
+import 'dart:js_interop';
 
 import '../../../sentry.dart';
 import 'enricher_event_processor.dart';
@@ -69,8 +70,7 @@ class WebEnricherEventProcessor implements EnricherEventProcessor {
 
   int? _getMemorySize() {
     // https://developer.mozilla.org/en-US/docs/Web/API/Navigator/deviceMemory
-    // ignore: invalid_null_aware_operator
-    final size = _window.navigator.deviceMemory?.toDouble();
+    final size = _window.navigator.safeDeviceMemory?.toDouble();
     final memoryByteSize = size != null ? size * 1024 * 1024 * 1024 : null;
     return memoryByteSize?.toInt();
   }
@@ -116,7 +116,15 @@ class WebEnricherEventProcessor implements EnricherEventProcessor {
   }
 }
 
-extension on web.Navigator {
-  // ignore: unused_element
-  external double? get deviceMemory;
+/// Some Navigator properties are not fully supported in all browsers.
+/// However, package:web does not provide a safe way to access these properties,
+/// and assumes they are always not null.
+///
+/// This extension provides a safe way to access these properties.
+///
+/// See: https://github.com/dart-lang/web/issues/326
+///      https://github.com/fluttercommunity/plus_plugins/issues/3391
+extension SafeNavigationGetterExtensions on web.Navigator {
+  @JS('deviceMemory')
+  external double? get safeDeviceMemory;
 }

packages/dart/test/event_processor/enricher/web_enricher_test.dart

@@ -5,6 +5,7 @@ import 'package:sentry/sentry.dart';
 import 'package:sentry/src/event_processor/enricher/web_enricher_event_processor.dart';
 import 'package:sentry/src/platform/mock_platform.dart';
 import 'package:test/test.dart';
+import 'package:web/web.dart' as web;
 
 import '../../mocks.dart';
 import '../../test_utils.dart';
@@ -195,6 +196,18 @@ void main() {
       expect(sentryOptions.eventProcessors.map((e) => e.runtimeType.toString()),
           contains('$WebEnricherEventProcessor'));
     });
+
+    test('SafeNavigationGetterExtensions safely accesses deviceMemory', () {
+      // Test that the extension can safely access deviceMemory without throwing
+      final navigator = web.window.navigator;
+
+      // This should not throw an exception even if deviceMemory is not supported
+      final deviceMemory = navigator.safeDeviceMemory;
+
+      // deviceMemory can be null if not supported by the browser
+      // or a double value if supported
+      expect(deviceMemory == null || deviceMemory > 0, isTrue);
+    });
   });
 }