fix(flutter): Skip Android worker reads after close

Return null for Android core worker read paths after shutdown so closed
workers do not fall back to JNI work on the main isolate.

Co-Authored-By: GPT-5.5 <noreply@openai.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

Author: 3 people

packages/flutter/lib/src/native/java/android_core_worker.dart

@@ -100,6 +100,8 @@ class AndroidCoreWorker {
   }
 
   FutureOr<List<DebugImage>?> loadDebugImages(SentryStackTrace stackTrace) {
+    if (_isClosed) return null;
+
     final instructionAddresses =
         stackTrace.frames.map((f) => f.instructionAddr).nonNulls.toList(
               growable: false,
@@ -140,6 +142,8 @@ class AndroidCoreWorker {
   }
 
   FutureOr<Map<String, dynamic>?> loadContexts() {
+    if (_isClosed) return null;
+
     final client = _worker;
     if (client == null) {
       return _loadContexts(automatedTestMode: _config.automatedTestMode);

packages/flutter/test/native/android_core_worker_test_real.dart

@@ -272,6 +272,20 @@ void main() {
       expect(await resultFuture, isNull);
     });
 
+    test('returns null for debug images after close', () async {
+      final fixture = _Fixture();
+      fixture.options.automatedTestMode = true;
+      final worker = fixture.getSut();
+      await worker.start();
+      await worker.close();
+
+      final result = worker.loadDebugImages(SentryStackTrace(frames: [
+        SentryStackFrame(instructionAddr: '0x1'),
+      ]));
+
+      expect(await Future<List<DebugImage>?>.value(result), isNull);
+    });
+
     test('requests native contexts', () async {
       final fixture = _Fixture();
       final worker = fixture.getSut();
@@ -303,6 +317,18 @@ void main() {
       expect(await resultFuture, isNull);
     });
 
+    test('returns null for native contexts after close', () async {
+      final fixture = _Fixture();
+      fixture.options.automatedTestMode = true;
+      final worker = fixture.getSut();
+      await worker.start();
+      await worker.close();
+
+      final result = worker.loadContexts();
+
+      expect(await Future<Map<String, dynamic>?>.value(result), isNull);
+    });
+
     test('sends breadcrumb update and awaits response', () async {
       final fixture = _Fixture();
       final worker = fixture.getSut();