Fix: Multiple FlutterError.onError calls in FlutterErrorIntegration

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Unreleased
 
 * Bump: sentry-android to v4.3.0 (#343)
+* Fix: Multiple FlutterError.onError calls in FlutterErrorIntegration (#345)
 
 # 4.1.0-nullsafety.0
 

flutter/lib/src/default_integrations.dart

@@ -34,9 +34,14 @@ class WidgetsFlutterBindingIntegration
 ///     and are stripped in release mode. See [Flutter build modes](https://flutter.dev/docs/testing/build-modes).
 ///     So they only get caught in debug mode.
 class FlutterErrorIntegration extends Integration<SentryFlutterOptions> {
+  /// Keep a reference to the original handler.
+  static FlutterExceptionHandler? defaultOnError;
+
   @override
   void call(Hub hub, SentryFlutterOptions options) {
-    final defaultOnError = FlutterError.onError;
+    if (defaultOnError == null && FlutterError.onError != null) {
+      defaultOnError = FlutterError.onError;
+    }
 
     FlutterError.onError = (FlutterErrorDetails errorDetails) async {
       dynamic exception = errorDetails.exception;
@@ -60,7 +65,7 @@ class FlutterErrorIntegration extends Integration<SentryFlutterOptions> {
 
         // call original handler
         if (defaultOnError != null) {
-          defaultOnError(errorDetails);
+          defaultOnError!(errorDetails);
         }
 
         // we don't call Zone.current.handleUncaughtError because we'd like
@@ -76,6 +81,14 @@ class FlutterErrorIntegration extends Integration<SentryFlutterOptions> {
 
     options.sdk.addIntegration('flutterErrorIntegration');
   }
+
+  @override
+  void close() {
+    /// Restore default
+    FlutterError.onError = defaultOnError;
+    defaultOnError = null;
+    super.close();
+  }
 }
 
 /// Load Device's Contexts from the iOS SDK.

flutter/test/default_integrations_test.dart

@@ -22,6 +22,7 @@ void main() {
 
   tearDown(() {
     _channel.setMockMethodCallHandler(null);
+    FlutterErrorIntegration.defaultOnError = null;
   });
 
   void _reportError({
@@ -75,6 +76,41 @@ void main() {
     expect(true, called);
   });
 
+  test('FlutterErrorIntegration captureEvent only called once', () async {
+    var numberOfDefaultCalls = 0;
+    final defaultError = (FlutterErrorDetails errorDetails) async {
+      numberOfDefaultCalls++;
+    };
+    FlutterError.onError = defaultError;
+
+    when(fixture.hub.captureEvent(captureAny))
+        .thenAnswer((_) => Future.value(SentryId.empty()));
+
+    final details = FlutterErrorDetails(exception: StateError('error'));
+
+    final errorIntegration = FlutterErrorIntegration();
+    errorIntegration.call(fixture.hub, fixture.options);
+    errorIntegration.call(fixture.hub, fixture.options);
+
+    FlutterError.reportError(details);
+
+    verify(await fixture.hub.captureEvent(captureAny)).called(1);
+    expect(numberOfDefaultCalls, 1);
+  });
+
+  test('FlutterErrorIntegration close restored default onError', () async {
+    final defaultOnError = (FlutterErrorDetails errorDetails) async {};
+    FlutterError.onError = defaultOnError;
+
+    final integrtion = FlutterErrorIntegration();
+    integrtion.call(fixture.hub, fixture.options);
+    expect(false, defaultOnError == FlutterError.onError);
+
+    integrtion.close();
+
+    expect(true, defaultOnError == FlutterError.onError);
+  });
+
   test('FlutterError do not capture if silent error', () async {
     _reportError(silent: true);